U.S. patent number 11,401,268 [Application Number 16/715,699] was granted by the patent office on 2022-08-02 for organic compound having improved luminescent properties, organic light emitting diode and organic light emitting device having the compound.
This patent grant is currently assigned to KOREA UNIVERSITY RESEARCH AND BUSINESS FOUNDATION, LG DISPLAY CO., LTD.. The grantee listed for this patent is Korea University Research and Business Foundation, LG Display Co., Ltd. Invention is credited to Dong-Hoon Choi, Su-Na Choi, Mallesham Godumala, Hyung-Jong Kim, Bo-Min Seo, Joong-Hwan Yang, Dae-Wi Yoon.
United States Patent |
11,401,268 |
Seo , et al. |
August 2, 2022 |
Organic compound having improved luminescent properties, organic
light emitting diode and organic light emitting device having the
compound
Abstract
An organic compound, an organic light emitting diode including
the compound, and an organic light emitting device including the
organic light emitting diode are disclosed. The organic compound
may include a fused hetero aromatic moiety having a p-type property
and an aza-acridine moiety having an n-type property bonded to the
fused hetero aromatic moiety via an aromatic or a hetero aromatic
linker. The organic compound has relatively high energy level since
it includes plural fused hetero aromatic rings. Holes and electrons
can be recombined in an emitting material layer in a balanced
manner since the organic compound has a bipolar property. The
organic light emitting diode and the organic light emitting device
including the organic compound have enhanced luminous efficiency
and luminous lifetime.
Inventors: |
Seo; Bo-Min (Paju-si,
KR), Yoon; Dae-Wi (Paju-si, KR), Yang;
Joong-Hwan (Paju-si, KR), Choi; Dong-Hoon
(Paju-si, KR), Choi; Su-Na (Paju-si, KR),
Kim; Hyung-Jong (Paju-si, KR), Godumala;
Mallesham (Paju-si, KR) |
Applicant: |
Name |
City |
State |
Country |
Type |
LG Display Co., Ltd
Korea University Research and Business Foundation |
Seoul
Seoul |
N/A
N/A |
KR
KR |
|
|
Assignee: |
LG DISPLAY CO., LTD. (Seoul,
KR)
KOREA UNIVERSITY RESEARCH AND BUSINESS FOUNDATION (Seoul,
KR)
|
Family
ID: |
1000006471920 |
Appl.
No.: |
16/715,699 |
Filed: |
December 16, 2019 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20200207760 A1 |
Jul 2, 2020 |
|
Foreign Application Priority Data
|
|
|
|
|
Dec 28, 2018 [KR] |
|
|
10-2018-0172143 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L
51/0061 (20130101); C07D 471/04 (20130101); H01L
51/0072 (20130101) |
Current International
Class: |
C07D
471/04 (20060101); H01L 51/00 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
105384759 |
|
Mar 2016 |
|
CN |
|
106414450 |
|
Feb 2017 |
|
CN |
|
107434796 |
|
Dec 2017 |
|
CN |
|
109956962 |
|
Jul 2019 |
|
CN |
|
3 029 037 |
|
Jun 2016 |
|
EP |
|
10-2014-0015385 |
|
Feb 2014 |
|
KR |
|
10-2014-0018101 |
|
Feb 2014 |
|
KR |
|
10-2014-0076521 |
|
Jun 2014 |
|
KR |
|
10-2018-0067950 |
|
Jun 2018 |
|
KR |
|
WO-2014021569 |
|
Feb 2014 |
|
WO |
|
WO-2018092928 |
|
May 2018 |
|
WO |
|
Other References
L Sicard et al., 123 The Journal of Physical Chemistry C,
19094-19104 (2019) (Year: 2019). cited by examiner .
Hawley's Condensed Chemical Dictionary (16th ed., 2016, R.J.
Larranaga ed.) (Year: 2016). cited by examiner .
MA Fox, Organic Chemistry, 133-134 (1997) (Year: 1997). cited by
examiner .
Luo et al., "Rational design of isophthalonitrile-based thermally
activated delayed fluorescence emitters for OLEDs with high
efficiency and slow efficiency roll-off", Dyes and Pigments. vol.
147, Dec. 2017, pp. 350-356. cited by applicant.
|
Primary Examiner: Pagano; Alexander R
Attorney, Agent or Firm: Birch, Stewart, Kolasch &
Birch, LLP
Claims
The invention claimed is:
1. An organic compound having the structure of Chemical Formula 1:
##STR00065## wherein: each of R.sub.1 and R.sub.2 is independently
protium, deuterium, tritium, linear or branched C.sub.1-C.sub.20
alkyl group, C.sub.1-C.sub.20 alkoxy group, C.sub.6-C.sub.30 aryl
group or C.sub.4-C.sub.30 hetero aryl group, or R.sub.1 and R.sub.2
form a C.sub.5-C.sub.30 spiro structure; each R.sub.3 is
independently protium, deuterium, tritium, linear or branched
C.sub.1-C.sub.20 alkyl group, C.sub.1-C.sub.20 alkoxy group,
C.sub.6-C.sub.30 aryl group or C.sub.4-C.sub.30 hetero aryl group,
or adjacent two groups among R.sub.3 form C.sub.4-C.sub.20 fused
aromatic or hetero aromatic ring; o is an integer from 0 to 4;
wherein X.sub.2 is a nitrogen atom (N); each of X.sub.1, X.sub.3
and X.sub.4 is independently CR.sub.4 or nitrogen atom (N), wherein
at least one of X.sub.1 to X.sub.4 is nitrogen atom, wherein
R.sub.4 is protium, deuterium, tritium, linear or branched
C.sub.1-C.sub.20 alkyl group, C.sub.1C.sub.20 alkoxy group,
C.sub.6-C.sub.30 aryl group or C.sub.4-C.sub.30 hetero aryl group,
or adjacent two groups among R.sub.4 form C.sub.4-C.sub.30 fused
aromatic or hetero aromatic ring; and each of Y.sub.1 to Y.sub.5 is
independently CR.sub.5 or nitrogen atom (N), wherein at least three
of Y.sub.1 to Y.sub.5 is CR.sub.5, wherein R.sub.5 is protium,
deuterium, tritium, linear or branched C.sub.1-C.sub.20 alkyl
group, C.sub.1-C.sub.20 alkoxy group or C.sub.10-C.sub.30 fused
group of a heterocycle ring and an aryl group, wherein the
C.sub.10-C.sub.30 fused group of a heterocycle ring and an aryl
group is unsubstituted or substituted with a group selected from
the group consisting of linear or branched C.sub.1-C.sub.20 alkyl
group, C.sub.1-C.sub.20 alkoxy group, C.sub.6-C.sub.30 aryl group,
C.sub.4-C.sub.30 hetero aryl group, C.sub.4-C.sub.30 aromatic or
hetero aromatic amino group and a combination thereof, fused with a
C.sub.4-C.sub.20 aromatic or hetero aromatic ring or linked by a
spiro structure of a C.sub.4-C.sub.20 aromatic or hetero aromatic
ring, wherein at least one R.sub.5 among Y.sub.1 to Y.sub.5 is
C.sub.10-C.sub.30 fused group of a heterocycle ring and an aryl
group unsubstituted or substituted with a group selected from the
group consisting of linear or branched C.sub.1-C.sub.20 alkyl
group, C.sub.1-C.sub.20 alkoxy group, C.sub.6-C.sub.30 aryl group,
C.sub.4-C.sub.30 hetero aryl group, C.sub.4-C.sub.30 aromatic or
hetero aromatic amino group and a combination thereof, fused with a
C.sub.4-C.sub.20 aromatic or hetero aromatic ring or linked by a
spiro structure of a C.sub.4-C.sub.20 aromatic or hetero aromatic
ring.
2. The organic compound of claim 1, wherein the C.sub.10-C.sub.30
fused group of a heterocycle ring and an aryl group constituting
R.sub.5 includes at least one nitrogen atom (N).
3. The organic compound of claim 1, wherein the C.sub.10-C.sub.30
fused group of a heterocycle ring and an aryl group constituting
R.sub.5 is selected from the group consisting of carbazolyl,
acridinyl, carbolinyl, spirofluorenocarbazolyl,
spirofluorenoacridinyl, phenazinyl, phenoxazinyl and
phenothiazinyl, and wherein each of the carbazolyl, the acridinyl,
the carbolinyl, the spirofluorenocarbazolyl, the
spirofluorenoacridinyl, the phenazinyl, the phenoxazinyl and the
phenothiazinyl is independently unsubstitued or substituted with a
group selected from the group consisting of linear or branched
C.sub.1-C.sub.20 alkyl group, C.sub.1-C.sub.20 alkoxy group,
C.sub.6-C.sub.30 aryl group, C.sub.4-C.sub.30 hetero aryl group,
C.sub.4-C.sub.30 aromatic or hetero aromatic amino group and a
combination thereof, fused with a C.sub.4-C.sub.20 aromatic or
hetero aromatic ring or linked by a spiro structure of a
C.sub.4-C.sub.20 aromatic or hetero aromatic ring,
respectively.
4. The organic compound of claim 1, having the structure of
Chemical Formula 2: ##STR00066## wherein: each of R.sub.11 and
R.sub.12 is independently linear or branched C.sub.1-C.sub.20
lalkyl group or C.sub.6-C.sub.20 aryl group; each of R.sub.13 and
R.sub.14 is independently protium, deuterium, tritium or linear or
branched C.sub.1-C.sub.20 alkyl group; o is an integer from 0 to 4;
p is an integer from 1 to 3; each of R.sub.15 to R.sub.18 is
independently protium, deuterium, tritium, linear or branched
C.sub.1-C.sub.20 alkyl group or C.sub.10-C.sub.30 fused group of a
heterocycle ring and an aryl group having at least one nitrogen
atom (N) on a ring, wherein the C.sub.10-C.sub.30 fused group of a
heterocycle ring and an aryl group is unsubstituted or substituted
a group selected from the group consisting of linear or branched
C.sub.1-C.sub.20 alkyl group, C.sub.6-C.sub.30 aryl group,
C.sub.4-C.sub.30 hetero aryl group, C.sub.4-C.sub.30 aromatic or
hetero aromatic amino group and a combination thereof, wherein at
least one of R.sub.15 to R.sub.18 is C.sub.10-C.sub.30 fused group
of a heterocycle ring and an aryl group having at least one
nitrogen atom (N) on the ring, wherein the C.sub.10-C.sub.30 fused
group of a heterocycle ring and an aryl group is unsubstituted or
substituted with a group selected from the group consisting of
linear or branched C.sub.1-C.sub.20 alkyl group, C.sub.6-C.sub.30
aryl group, C.sub.4-C.sub.30 hetero aryl group, C.sub.4-C.sub.30
aromatic or hetero aromatic amino group and a combination thereof;
Y is nitrogen atom (N) or CR.sub.19, wherein R.sub.19 is protium,
deuterium, tritium or linear or branched C.sub.1-C.sub.20 alkyl
group.
5. The organic compound of claim 1, having the structure of
Chemical Formula 3: ##STR00067## ##STR00068## ##STR00069##
##STR00070## ##STR00071## ##STR00072## ##STR00073## ##STR00074##
##STR00075## ##STR00076## ##STR00077## ##STR00078## ##STR00079##
##STR00080## ##STR00081## ##STR00082## ##STR00083## ##STR00084##
##STR00085## ##STR00086## ##STR00087## ##STR00088##
6. An organic lightemitting diode, comprising: a first electrode; a
second electrode facing the first electrode; at least one emitting
unit disposed between the first and second electrodes and wherein
the at least one emitting unit comprises an emitting material
layer, wherein the emitting material layer comprises an organic
compound having the structure of Chemical Formula 1: ##STR00089##
wherein: each of R.sub.1 and R.sub.2 is independently protium,
deuterium, tritium, linear or branched C.sub.1-C.sub.20, alkyl
group, C.sub.1-C.sub.20 alkoxy group, C.sub.6-C.sub.30 aryl group
or C.sub.4-C.sub.30 hetero aryl group, or R.sub.1 and R.sub.2 form
C.sub.5-C.sub.30 spiro structure; each R.sub.3 is independently
protium, deuterium, tritium, linear or branched C.sub.1-C.sub.20
alkyl group, C.sub.1-C.sub.20 alkoxy group, C.sub.6-C.sub.30 aryl
group or C.sub.4-C.sub.30 hetero aryl group, or adjacent two groups
among R.sub.3 form C.sub.4-C.sub.20 fused aromatic or hetero
aromatic ring; o is an integer from 0 to 4; wherein X.sub.2 is a
nitrogen atom (N): each of X.sub.1, X.sub.3 and X.sub.4 is
independently CR.sub.4 or nitrogen atom (N), wherein at least one
of X.sub.1 to X.sub.4 is nitrogen atom, wherein R.sub.4 is protium,
deuterium, tritium, linear or branched C.sub.1-C.sub.20 alkyl
group, C.sub.1-C.sub.20 alkoxy group, C.sub.6-C.sub.30 aryl group
or C.sub.4-C.sub.30 hetero aryl group, or adjacent two groups among
R.sub.4 form C.sub.4-C.sub.30 fused aromatic or hetero aromatic
ring; each of Y.sub.1 to Y.sub.5 is independently CR.sub.5 or
nitrogen atom (N), wherein at least three of Y.sub.1 to Y.sub.5 is
CR.sub.5, wherein R.sub.5 is protium, deuterium, tritium, linear or
branched. C.sub.1-C.sub.20 alkyl group, C.sub.1-C.sub.20 alkoxy
group or C.sub.10-C.sub.30 fused group of a heterocycle ring and an
aryl group, wherein the C.sub.10-C.sub.30 fused group of a
heterocycle ring and an aryl group is unsubstituted or substituted
with a group selected from the group consisting of linear or
branched C.sub.1-C.sub.20 alkyl group, C.sub.1-C.sub.20 alkoxy
group, C.sub.6-C.sub.30 aryl group, C.sub.4-C.sub.30 hetero aryl
group, C.sub.4-C.sub.30 aromatic or hetero aromatic amino group and
combination thereof, fused with a C.sub.4-C.sub.20 aromatic or
hetero aromatic ring or linked by a spiro structure of a
C.sub.4-C.sub.20 aromatic or hetero aromatic ring, wherein at least
one R.sub.5 among Y.sub.1 to Y.sub.5 is C.sub.10-C.sub.30 fused
group of a heterocycle ring and an aryl group unsubstituted or
substituted with a group selected from the group consisting of
linear or branched C.sub.1-C.sub.20 alkyl group, C.sub.1-C.sub.20
alkoxy group, C.sub.6-C.sub.30 aryl group, C.sub.4-C.sub.30 hetero
aryl group, C.sub.4-C.sub.30 aromatic or hetero aromatic amino
group and combination thereof, fused with a C.sub.4-C.sub.20
aromatic or hetero aromatic ring or linked by a spiro structure of
a C.sub.4-C.sub.20 aromatic or hetero aromatic ring.
7. The organic light emitting diode of claim 6, wherein the
C.sub.10-C.sub.30 fused group of a heterocycle ring and an aryl
group constituting R.sub.5 includes at least one nitrogen atom
(N).
8. The organic light emitting diode of claim 6, wherein the
C.sub.10-C.sub.30 fused group of a heterocycle ring and an aryl
group constituting R.sub.5 is selected from the group consisting of
carbazolyl, acridinyl, carbolinyl, spirofluorenocarbazolyl,
spirofluorenoacridinyl, phenazinyl, phenoxazinyl and
phenothiazinyl, and wherein each of the carbazolyl, the acridinyl,
the carbolinyl, the spirofluorenocarbazolyl, the
spirofluorenoacridinyl, the phenazinyl, the phenoxazinyl and the
phenothiazinyl is independently unsubstitued or substituted with a
group selected from the group consisting of linear or branched
C.sub.1-C.sub.20 alkyl group, C.sub.1-C.sub.20 alkoxy group,
C.sub.6-C.sub.30 aryl group, C.sub.4-C.sub.30 hetero aryl group,
C.sub.4-C.sub.30 aromatic or hetero aromatic amino group and a
combination thereof, fused with a C.sub.4-C.sub.20 aromatic or
hetero aromatic ring or linked by a spiro structure of a
C.sub.4-C.sub.20 aromatic or hetero aromatic ring,
respectively.
9. The organic light emitting diode of claim 6, wherein the organic
compound has the structure of Chemical Formula 2: ##STR00090##
wherein: each of R.sub.11 and R.sub.12 is independently linear or
branched C.sub.1-C.sub.20 alkyl group or C.sub.6-C.sub.20 aryl
group; each of R.sub.13 and R.sub.14 is independently protium,
deuterium, tritium or linear or branched C.sub.1-C.sub.20 alkyl
group; o is an integer from 0 to 4; p is an integer from 1 to 3;
each of R.sub.15 to R.sub.18 is independently protium, deuterium,
tritium, linear or branched C.sub.1-C.sub.20 alkyl group or
C.sub.10-C.sub.30 fused group of a heterocycle ring and an aryl
group having at least one nitrogen atom (N) on a ring, wherein the
C.sub.10-C.sub.30 fused group of a heterocycle ring and an aryl
group is a unsubstituted or substituted group selected from the
group consisting of linear or branched C.sub.1-C.sub.20 alkyl
group, C.sub.6-C.sub.30 aryl group, C.sub.4-C.sub.30 hetero aryl
group, C.sub.4-C.sub.30 aromatic or hetero aromatic amino group and
combination thereof, wherein at least one of R.sub.15 to R.sub.18
is C.sub.10-C.sub.30 fused group of a heterocycle ring and an aryl
group having at least one nitrogen atom (N) on the ring, wherein
the C.sub.10-C.sub.30 fused group of a heterocycle ring and an acyl
group is a unsubstituted or substituted with a group selected from
the group consisting of linear or branched C.sub.1-C.sub.20 alkyl
group, C.sub.6-C.sub.30 aryl group, C.sub.4-C.sub.30 hetero aryl
group, C.sub.4-C.sub.30 aromatic or hetero aromatic amino group and
combination thereof; Y is nitrogen atom (N) or CR.sub.19, wherein
R.sub.19 is protium, deuterium, tritium or linear or branched
C.sub.1-C.sub.20 alkyl group.
10. The organic light emitting diode of claim 6, wherein the
emitting material layer comprises a first host and a first dopant,
and wherein the first host comprises the organic compound.
11. The organic light emitting diode of claim 10, wherein an energy
level bandgap between an excited state singlet energy level
(S.sub.1.sup.TD) and an excited state triplet energy level
(T.sub.1.sup.TD) of the first dopant is equal to or less than about
0.3 eV.
12. The organic light emitting diode of claim 10, wherein an
excited state singlet energy level (S.sub.1.sup.H) and an excited
state triplet energy level (T.sub.1.sup.H) of the first host is
higher than excited state singlet energy level (S.sub.1.sup.TD) and
an excited state triplet energy level (T.sub.1.sup.TD) of the first
dopant, respectively.
13. The organic light emitting diode of claim 10, the emitting
material layer further comprises a second dopant, and wherein an
excited state singlet energy level (S.sub.1.sup.TD) of the first
dopant is higher than an excited state singlet energy level
(S.sub.1.sup.TD) of the second dopant.
14. The organic light emitting diode of claim 6, wherein the
emitting material layer comprises a first emitting material layer
disposed between the first and second electrodes and a second
emitting material layer disposed between the first electrode and
the first emitting material layer or between the first emitting
material layer and the second electrode.
15. The organic light emitting diode of claim 14, wherein the first
emitting material layer comprises a first host and a first dopant,
and wherein the first host comprises the organic compound.
16. The organic light emitting diode of claim 15, wherein the
second emitting material layer comprises a second host and a second
dopant, and wherein an excited state singlet energy level
(S.sub.1.sup.TD) of the first dopant is higher than an excited
state singlet energy level (S.sub.1.sup.TD) of the second
dopant.
17. The organic light emitting diode of claim 14, the emitting
material layer further comprises a third emitting material layer
disposed oppositely to the second emitting material layer with
respect to the first emitting material layer.
18. The organic light emitting diode of claim 17, wherein the first
emitting material layer comprises a first host and a first dopant,
the second emitting material layer comprises a second host and a
second dopant and the third emitting material layer includes a
third host and a third dopant, and wherein an excited state singlet
energy level (S.sub.1.sup.TD) of the first dopant is higher than
each of excited state singlet energy levels (S.sub.1.sup.FD1 and
S.sub.1.sup.FD2) of the second and third dopants, respectively.
19. The organic light emitting diode of claim 6, wherein the at
least one emitting unit comprises a first emitting unit disposed
between the first and second electrodes and a second emitting unit
disposed between the first emitting unit and the second electrode,
wherein the first emitting unit comprises a lower emitting material
layer and the second emitting unit comprises an upper emitting
material layer, and wherein at least one of the lower emitting
material layer and the upper emitting material layer includes the
organic compound, and the organic light emitting diode further
comprises a charge generation layer disposed between the first and
second emitting units.
20. An organic light emitting device, comprising: a substrate; a
thin-film transistor on the substrate; and the organic light
emitting diode according to claim 6, wherein the organic light
emitting diode is connected to the thin film transistor.
21. The organic compound of claim 1, wherein each of X.sub.1,
X.sub.3 and X.sub.4 is independently CR.sub.4.
22. The organic light emitting diode of claim 6, wherein each of
X.sub.1, X.sub.3 and X.sub.4 is independently CR.sub.4.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit under 35 U.S.C. .sctn. 119(a)
of Korean Patent Application No. 10-2018-0172143, filed in Republic
of Korea on Dec. 28, 2018, which is incorporated herein by
reference in its entirety.
BACKGROUND OF THE INVENTION
Technical Field
The present disclosure relates to an organic compound, and more
specifically, to an organic compound having enhanced luminescent
properties, an organic light emitting diode and an organic light
emitting device including the compound.
Description of the Related Art
Among the flat display devices used widely in present, an organic
light emitting diode (OLED) has come into the spotlight as a
display device replacing rapidly a liquid crystal display device
(LCD). In the OLED, when electrical charges are injected into an
emission layer between an electron injection electrode (i.e.,
cathode) and a hole injection electrode (i.e., anode), electrical
charges are combined to be paired, and then emit light as the
combined electrical charges are disappeared.
The OLED can be formed as a thin film less than 2000 .ANG. and
implement unidirectional or bidirectional images as electrode
configurations. In addition, OLED can be formed even on a flexible
transparent substrate such as a plastic substrate so that OLED can
implement a flexible or foldable display with ease. Moreover, the
OLED can be driven at a lower voltage of 10 V or less. Besides, the
OLED has relatively lower power consumption for driving compared to
plasma display panel and inorganic electroluminescent devices, and
color purity thereof is very high.
Since only singlet excitons in the prior art common fluorescent
material can be involved in luminous process, luminous efficiency
of the common fluorescent material is low. On the contrary, the
prior art phosphorescent material in which triplet excitons as well
as singlet excitons participate in the luminous process showed high
luminous efficiency compared to the common fluorescent material.
However, since metal complex as a representative phosphorescent
material has a short luminous lifetime, its commercial application
has been limited. Particularly, the organic compound for
implementing blue luminescence has deficient luminescent properties
and short luminous lifetime.
SUMMARY OF THE INVENTION
Accordingly, the present disclosure is directed to an organic
compound, an organic light emitting diode and an organic light
emitting device including the organic compounds that can reduce one
or more of the problems due to the limitations and disadvantages of
the related art.
An object of the present disclosure is to provide an organic
compound that enhances its luminescent properties, and an organic
light emitting diode and an organic light emitting device
introducing the organic compound.
Additional features and advantages of the disclosure will be set
forth in the description which follows, and in part will be
apparent from the description, or may be learned by practice of the
disclosure. The objectives and other advantages of the disclosure
will be realized and attained by the structure particularly pointed
out in the written description and claims hereof as well as the
appended drawings.
According to an aspect, the present disclosure provides an organic
compound having the following Chemical Formula 1:
##STR00001##
wherein each of R.sub.1 and R.sub.2 is independently protium,
deuterium, tritium, linear or branched C.sub.1-C.sub.20 alkyl
group, C.sub.1-C.sub.20 alkoxy group, C.sub.6-C.sub.30 aryl group
or C.sub.4-C.sub.30 hetero aryl group, or R.sub.1 and R.sub.2 form
C.sub.5-C.sub.30 spiro structure; R.sub.3 is protium, deuterium,
tritium, linear or branched C.sub.1-C.sub.20 alkyl group,
C.sub.1-C.sub.20 alkoxy group, C.sub.6-C.sub.30 aryl group or
C.sub.4-C.sub.30 hetero aryl group, or adjacent two groups among
R.sub.3 form C.sub.4-C.sub.20 fused aromatic or hetero aromatic
ring; o is an integer of 0 to 4; each of X.sub.1 to X.sub.4 is
independently CR.sub.4 or nitrogen atom (N), wherein at least one
of X.sub.1 to X.sub.4 is nitrogen atom, wherein R.sub.4 is protium,
deuterium, tritium, linear or branched C.sub.1-C.sub.20 alkyl
group, C.sub.1-C.sub.20 alkoxy group, C.sub.6-C.sub.30 aryl group
or C.sub.4-C.sub.30 hetero aryl group, or adjacent two groups among
R.sub.4 form C.sub.4-C.sub.30 fused aromatic or hetero aromatic
ring; each of Y.sub.1 to Y.sub.5 is independently CR.sub.5 or
nitrogen atom (N), wherein at least three of Y.sub.1 to Y.sub.5 is
CR.sub.5, wherein R.sub.5 is protium, deuterium, tritium, linear or
branched C.sub.1-C.sub.20 alkyl group, C.sub.1-C.sub.20 alkoxy
group or C.sub.10-C.sub.30 fused hetero aryl group, wherein the
C.sub.10-C.sub.30 fused hetero aryl group is unsubstituted or
substituted with a group selected from the group consisting of
linear or branched C.sub.1-C.sub.20 alkyl group, C.sub.1-C.sub.20
alkoxy group, C.sub.6-C.sub.30 aryl group, C.sub.4-C.sub.30 hetero
aryl group, C.sub.4-C.sub.30 aromatic or hetero aromatic amino
group and combination thereof, fused with a C.sub.4-C.sub.20
aromatic or hetero aromatic ring or linked by a spiro structure of
a C.sub.4-C.sub.20 aromatic or hetero aromatic ring, wherein at
least one R.sub.5 among Y.sub.1 to Y.sub.5 is C.sub.10-C.sub.30
fused hetero aryl group unsubstituted or substituted with a group
selected from the group consisting of linear or branched
C.sub.1-C.sub.20 alkyl group, C.sub.1-C.sub.20 alkoxy group,
C.sub.6-C.sub.30 aryl group, C.sub.4-C.sub.30 hetero aryl group,
C.sub.4-C.sub.30 aromatic or hetero aromatic amino group and
combination thereof, fused with a C.sub.4-C.sub.20 aromatic or
hetero aromatic ring or linked by a spiro structure of a
C.sub.4-C.sub.20 aromatic or hetero aromatic ring.
According to another aspect, the present disclosure provides an
organic light emitting diode (OLED) that comprises a first
electrode; a second electrode facing the first electrode; and at
least one emitting unit disposed between the first and second
electrodes and including an emitting material layer, wherein the
emitting material layer comprises the above organic compound.
According to still another aspect, the present disclosure provides
an organic light emitting device that comprises a substrate and the
OLED disposed over the substrate, as described above.
It is to be understood that both the foregoing general description
and the following detailed description are examples and are
explanatory and are intended to provide further explanation of the
disclosure as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are included to provide a further
understanding of the disclosure, are incorporated in and constitute
a part of this specification, illustrate implementations of the
disclosure and together with the description serve to explain the
principles of embodiments of the disclosure.
FIG. 1 is a schematic cross-sectional view illustrating an organic
light emitting display device of the present disclosure.
FIG. 2 is a schematic cross-sectional view illustrating an organic
light emitting diode in accordance with an exemplary embodiment of
the present disclosure.
FIG. 3 is s schematic diagram illustrating luminous mechanism of
the delayed fluorescent material in an EML in accordance with an
exemplary embodiment of the present disclosure.
FIG. 4 is a schematic diagram illustrating luminous mechanism by
energy level bandgap between luminous materials in accordance with
an exemplary embodiment of the present disclosure.
FIG. 5 is a schematic cross-sectional view illustrating an organic
light emitting diode in accordance with another exemplary
embodiment of the present disclosure.
FIG. 6 is a schematic diagram illustrating luminous mechanism by
energy level bandgap among luminous materials in accordance with
another exemplary embodiment of the present disclosure.
FIG. 7 is a schematic cross-sectional view illustrating an organic
light emitting diode in accordance with another exemplary
embodiment of the present disclosure.
FIG. 8 is a schematic diagram illustrating luminous mechanism by
energy level bandgap among luminous materials in accordance with
another exemplary embodiment of the present disclosure.
FIG. 9 is a schematic cross-sectional view illustrating an organic
light emitting diode in accordance with another exemplary
embodiment of the present disclosure.
FIG. 10 is a schematic diagram illustrating luminous mechanism by
energy level bandgap among luminous materials in accordance with
another exemplary embodiment of the present disclosure.
FIG. 11 is a schematic cross-section view illustrating an organic
light emitting diode in accordance with another exemplary
embodiment of the present disclosure.
DETAILED DESCRIPTION OF THE INVENTION
Reference will now be made in detail to aspects of the disclosure,
examples of which are illustrated in the accompanying drawings.
Organic Compound
An organic compound applied in an organic light emitting diode
should have excellent luminescent properties and maintain stable
properties during driving the diode. Particularly, luminous
material within an organic light emitting diode is the most
important factor for determining the luminous efficiency of the
diode. Accordingly, the luminous material should have high quantum
efficiency as well as mobility for holes and electrons and form
stably excitons. An organic compound of the present disclosure has
a structure of an aza-acridine moiety and a fused hetero aryl
moiety linked to the aza-acridine moiety via aromatic or hetero
aromatic linker. The organic compound of the present disclosure may
have the following structure of Chemical Formula 1:
##STR00002##
In Chemical Formula 1, each of R.sub.1 and R.sub.2 is independently
protium, deuterium, tritium, linear or branched C.sub.1-C.sub.20
alkyl group, C.sub.1-C.sub.20 alkoxy group, C.sub.6-C.sub.30 aryl
group or C.sub.4-C.sub.30 hetero aryl group, or R.sub.1 and R.sub.2
form C.sub.5-C.sub.30 spiro structure. R.sub.3 is protium,
deuterium, tritium, linear or branched C.sub.1-C.sub.20 alkyl
group, C.sub.1-C.sub.20 alkoxy group, C.sub.6-C.sub.30 aryl group
or C.sub.4-C.sub.30 hetero aryl group, or adjacent two groups among
R.sub.3 form C.sub.4-C.sub.20 fused aromatic or hetero aromatic
ring. o is an integer of 0 to 4. Each of X.sub.1 to X.sub.4 is
independently CR.sub.4 or nitrogen atom (N), wherein at least one
of X.sub.1 to X.sub.4 is nitrogen atom, wherein R.sub.4 is protium,
deuterium, tritium, linear or branched C.sub.1-C.sub.20 alkyl
group, C.sub.1-C.sub.20 alkoxy group, C.sub.6-C.sub.30 aryl group
or C.sub.4-C.sub.30 hetero aryl group, or adjacent two groups among
R.sub.4 form C.sub.4-C.sub.30 fused aromatic or hetero aromatic
ring. Each of Y.sub.1 to Y.sub.5 is independently CR.sub.5 or
nitrogen atom (N), wherein at least three of Y.sub.1 to Y.sub.5 is
CR.sub.5, wherein R.sub.5 is protium, deuterium, tritium, linear or
branched C.sub.1-C.sub.20 alkyl group, C.sub.1-C.sub.20 alkoxy
group or C.sub.10-C.sub.30 fused hetero aryl group, wherein the
C.sub.10-C.sub.30 fused hetero aryl group is unsubstituted or
substituted with a group selected from the group consisting of
linear or branched C.sub.1-C.sub.20 alkyl group, C.sub.1-C.sub.20
alkoxy group, C.sub.6-C.sub.30 aryl group, C.sub.4-C.sub.30 hetero
aryl group, C.sub.4-C.sub.30 aromatic or hetero aromatic amino
group and combination thereof, fused with a C.sub.4-C.sub.20
aromatic or hetero aromatic ring or linked by a spiro structure of
a C.sub.4-C.sub.20 aromatic or hetero aromatic ring, wherein at
least one R.sub.5 among Y.sub.1 to Y.sub.5 is C.sub.10-C.sub.30
fused hetero aryl group unsubstituted or substituted with a group
selected from the group consisting of linear or branched
C.sub.1-C.sub.20 alkyl group, C.sub.1-C.sub.20 alkoxy group,
C.sub.6-C.sub.30 aryl group, C.sub.4-C.sub.30 hetero aryl group,
C.sub.4-C.sub.30 aromatic or hetero aromatic amino group and
combination thereof, fused with a C.sub.4-C.sub.20 aromatic or
hetero aromatic ring or linked by a spiro structure of a
C.sub.4-C.sub.20 aromatic or hetero aromatic ring.
As used herein, the term "unsubstituted" means that hydrogen atom
is bonded, and in this case hydrogen atom includes protium,
deuterium and tritium.
The substituent as used herein may include, but are not limited to,
C.sub.1-C.sub.20 alkyl group unsubstituted or substituted with
halogen, C.sub.1-C.sub.20 alkoxy group unsubstituted or substituted
with halogen, halogen, cyano group, --CF.sub.3, hydroxyl group,
carboxyl group, carbonyl group, amino group, C.sub.1-C.sub.20 alkyl
amino group, C.sub.6-C.sub.30 aryl amino group, C.sub.4-C.sub.30
hetero aryl amino group, nitro group, hydrazyl group, sulfonyl
group, C.sub.5-C.sub.30 alkyl silyl group, C.sub.5-C.sub.30 alkoxy
silyl group, C.sub.3-C.sub.30 cycloalkyl silyl group,
C.sub.6-C.sub.30 aryl silyl group, C.sub.4-C.sub.30 hetero aryl
silyl group, C.sub.6-C.sub.30 aryl group and C.sub.4-C.sub.30
hetero aryl group. As an example, when each of R.sub.1 to R.sub.6
is independently substituted with alkyl group, the alkyl group may
be linear or branched C.sub.1-C.sub.20 alkyl group, and preferably
linear or branched C.sub.1-C.sub.10 alkyl group.
As used herein, the term "hetero" described in "hetero aromatic
ring", "hetero aromatic group", "hetero alicyclic ring", "hetero
cyclic alkyl group", "hetero aryl group", "hetero aralkyl group",
"hetero aryloxyl group", "hetero aryl amino group", "hetero arylene
group", "hetero aralkylene group", "hetero aryloxylene group", and
the likes means that at least one carbon atoms, for example 1 to 5
carbon atoms, forming such aromatic or alicyclic rings are replaced
with at least one hetero atoms selected from the group consisting
of N, O, S and combination thereof.
As illustrated in Chemical Formula 1, the organic compound of the
present disclosure includes an aza-acridine moiety including at
least one nitrogen atom on a side fused ring within the molecule.
The aza-acridine moiety bonds to the C.sub.10-C.sub.30 fused hetero
aryl moiety R.sub.5 via an aromatic or hetero aromatic linker
including Y.sub.1 to Y.sub.5. In one exemplary embodiment, the
C.sub.10-C.sub.30 fused hetero aryl group constituting R.sub.5 in
Chemical Formula 1 may include at least one nitrogen atom. For
example, the C.sub.10-C.sub.30 fused hetero aryl group constituting
R.sub.5 may be, but are not limited to, selected from the group
consisting of carbazolyl, acridinyl, carbolinyl,
spirofluorenocarbazolyl, spirofluorenoacridinyl, phenazinyl,
phenoxazinyl and phenothiazinyl.
The aza-acridine moiety in the organic compound of Chemical Formula
1 has excellent electron bonding ability, the aza-acridine moiety
may have n-type property inducing electron injection and
transportation. Since the C.sub.10-C.sub.30 fused hetero aryl
moiety has excellent hole bonding ability, the C.sub.10-C.sub.30
fused hetero aryl moiety may have p-type property inducing hole
injection and transportation. In other word, the organic compound
having the structure of Chemical Formula 1 may have bi-polar
property.
In one exemplary embodiment, when each of R.sub.1 to R.sub.4 is
independently C.sub.6-C.sub.30 aryl group or R.sub.5 is substituted
with C.sub.6-C.sub.30 aryl group, each of the C.sub.6-C.sub.30 aryl
group may independently be, but are not limited to, unfused or
fused aryl group such as phenyl, biphenyl, terphenyl, naphthyl,
anthracenyl, pentalenyl, indenyl, indeno-indenyl, heptalenyl,
biphenylenyl, indacenyl, phenalenyl, phenanthrenyl,
benzo-phenanthrenyl, dibenzo-phenanthrenyl, azulenyl, pyreneyl,
fluoranthenyl, triphenylenyl, chrysenyl, tetraphenyl, tetracenyl,
pleiadenyl, picenyl, pentaphenyl, pentacenyl, fluorenyl,
indeno-fluorenyl or spiro-fluorenyl.
In an alternative embodiment, when each of R.sub.1 to R.sub.4 is
independently C.sub.4-C.sub.30 hetero aryl group or R.sub.5 is
substituted with C.sub.4-C.sub.30 hetero aryl group, each of the
C.sub.4-C.sub.30 hetero aryl group may independently be, but are
not limited to, unfused or fused hetero aryl group such as
pyrrolyl, pyridinyl, pyrimidinyl, pyrazinyl, pyridazinyl,
triazinyl, tetrazinyl, imidazolyl, pyrazolyl, indolyl, iso-indolyl,
indazolyl, indolizinyl, pyrrolizinyl, carbazolyl, benzo-carbazolyl,
dibenzo-carbazolyl, indolo-carbazolyl, indeno-carbazolyl,
benzofuro-carbazolyl, benzothieno-carbazolyl, quinolinyl,
iso-quinolinyl, phthalazinyl, quinoxalinyl, cinnolinyl,
quinazolinyl, quinolizinyl, purinyl, benzo-quinolinyl,
benzo-iso-quinolinyl, benzo-quinazolinyl, benzo-quinoxalinyl,
acridinyl, phenanthrolinyl, perimidinyl, phenanthridinyl,
pteridinyl, naphthidinyl, furanyl, pyranyl, oxazinyl, oxazolyl,
oxadiazolyl, triazolyl, dioxinyl, benzo-furanyl, dibenzo-furanyl,
thiopyranyl, xanthenyl, chromenyl, iso-chromenyl, thioazinyl,
thiophenyl, benzo-thiophenyl, dibenzo-thiophenyl, difuro-pyrazinyl,
benzofuro-dibenzo-furanyl, benzothieno-benzo-thiophenyl,
benzothieno-dibenzo-furanyl, benzothieno-benzo-furanyl or
N-substituted spiro-fluorenyl.
In one exemplary embodiment, the C.sub.6-C.sub.30 aryl group or the
C.sub.4-C.sub.30 hetero aryl group, which constitutes each of
R.sub.1 to R.sub.4 or substitute to R.sub.5, may have 1, 2 or 3
aromatic or hetero aromatic ring. When the number of the aromatic
or hetero aromatic rings constituting each of R.sub.1 to R.sub.4 or
substituting to R.sub.5 is increased, the conjugated structure
within the entire organic compound becomes excessively long, so
that the bandgap of the organic compound may be excessively
reduced. As an example, when each of R.sub.1 to R.sub.4 is
independently aromatic or hetero aromatic group or R.sub.5 is
substituted with aromatic or hetero aromatic group, each of the
aromatic or hetero aromatic rings may be independently, but are not
limited to, phenyl, biphenyl, naphthyl, anthracenyl, pyrrolyl,
triazinyl, imidazolyl, pyrazolyl, pyridinyl, pyrazinyl,
pyrimidinyl, pyridazinyl, furanyl, benzo-furanyl, dibenzo-furanyl,
thiophenyl, benzo-thiophenyl, dibenzo-thiophenyl, carbazolyl,
acridinyl, carbolinyl, phenazinyl, phenoxazinyl and/or
phenothiazinyl.
In another exemplary embodiment, adjacent two groups among R.sub.3
or R.sub.4 may independently form a C.sub.4-C.sub.20 fused aromatic
or hetero aromatic ring and/or a R.sub.5 may be fused with
C.sub.4-C.sub.20 fused aromatic or hetero aromatic ring. In this
case, the C.sub.4-C.sub.20 fused aromatic or hetero aromatic ring
may include, but are not limited to, a fused aryl ring such as
fused phenyl ring, a fused naphthyl ring and/or a fused indeno ring
or a fused hetero aryl ring such as a fused pyridyl ring, a fused
pyrimidyl ring and/or a fused indolyl ring.
As an example, adjacent two groups among R.sub.3 or R.sub.4 may
independently form a C.sub.4-C.sub.20 fused aromatic or hetero
aromatic ring. In this case, the aza-acridine moiety may be fused
with an aromatic or hetero aromatic ring to form a benzo
aza-acridine moiety, a dibenzo aza-acridine moiety, a benzofuro
aza-acridine moiety, a benzothieno acridine moiety, a pyrido
aza-acridine moiety, an indeno aza-acridine moiety and/or an indolo
aza-acridine moiety, but are not limited thereto.
In another exemplary embodiment, the C.sub.10-C.sub.30 fused hetero
aryl moiety constituting R.sub.5 may be further fused with another
aromatic or hetero aromatic ring to form a benzo
carbazole/acridine/carboline/phenazine/phenoxazine/phenothiazine
moiety, a dibenzo
carbazole/acridine/carboline/phenazine/phenoxazine/phenothiazin- e
moiety, a benzofuro
carbazole/acridine/carboline/phenazine/phenoxazine/phenothiazine
moiety, a benzothieno
carbazole/acridine/carboline/phenazine/phenoxazine/phenothiazine
moiety, a pyrido
carbazole/acridine/carboline/phenazine/phenoxazine/phenothiazine
moiety, an indeno
carbazole/acridine/carboline/phenazine/phenoxazine/phenothiazine
moiety and/or an indolo
carbazole/acridine/carboline/phenazine/phenoxazine/phenothiazine
moiety.
In still another exemplary embodiment, R.sub.1 and R.sub.2 may form
a C.sub.5-C.sub.30 spiro structure and/or the C.sub.10-C.sub.30
fused hetero aryl group constituting R.sub.5 may be linked by a
spiro structure of a C.sub.4-C.sub.20 aromatic or hetero aromatic
ring. The spiro structure is not limited to a particular structure,
but may include a spiro-fluorene structure and a
spiro-benzofluorene structure, each of which is unsubstituted or
substituted with C.sub.1-C.sub.20 linear or branched alkyl group,
C.sub.6-C.sub.30 aromatic group, C.sub.4-C.sub.30 hetero aromatic
group, C.sub.6-C.sub.30 aromatic amino group and/or
C.sub.4-C.sub.30 hetero aromatic amino group.
Since the organic compound having the structure of Chemical Formula
1 includes the fused hetero aryl moiety, which has the p-type
property, and the aza-acridine moiety, which has the n-type
property, the organic compound has excellent affinity to the holes
as well as electrons. Accordingly, when the organic compound having
the structure of Chemical Formulae 1 and 2 is applied an emitting
material layer (EML), a recombination zone where holes and electros
form an exciton is located in the middle of the EML, not in an
interface between the EML and an electron transport layer (ETL) or
a hole blocking layer (HBL).
In addition, since the organic compound having the structure of
Chemical Formula 1 includes plural fused aromatic or hetero
aromatic rings, each of which has a rigid conformational structure,
the organic compound has an excellent thermal resistance property.
The organic compound having the structure of Chemical Formula 1 has
relatively high excited state singlet and triplet energy levels.
Moreover, the organic compound has a relatively deep (or low)
highest occupied molecular orbital (HOMO) energy level and a
relatively shallow (or high) lowest unoccupied molecular orbital
(LUMO) energy level. In other words, an energy level bandgap (Eg)
between the HOMO energy level and the LUMO energy level of the
organic compound is wide. As an example, the organic compound
having the structure of Chemical Formula 1 may have the HOMO energy
level and the LUMO energy level suitable for use as a luminous
material, for example, a host. As an example, when the organic
compound is used together with a delayed fluorescent material in
the EML, the driving voltage of the OLED may be lowered to reduce
the power consumption. Accordingly, the stress applied to the OLED
owing to the increase in driving voltage is reduced, thereby
improving luminous efficiency and the luminous lifetime of the
OLED.
In one exemplary embodiment, the organic compound having the
structure of Chemical Formula 1 may have an excited state singlet
energy level S.sub.1, but are not limited to, equal to or higher
than about 3.1 eV and an excited state triplet energy level
T.sub.1, but are not limited to, equal to or higher than about 2.7
eV. In addition, the organic compound having the structure of
Chemical Formula 1 may have a HOMO energy level, but are not
limited to, between about -5.5 eV and about -6.5 eV, and preferably
between about -5.7 eV and about -6.3 eV, and have a LUMO energy
level, but are not limited to, between about -1.5 eV and about -3.0
eV, and preferably between about -2.0 eV and about -2.5 eV.
Further, the organic compound having the structure of Chemical
Formula 1 may have an energy level bandgap (Eg) between the HOMO
energy level and the LUMO energy level, but are not limited to,
between about 3.0 eV and about 4.5 eV, and preferably between about
3.0 eV and about 4.2 eV.
In one exemplary embodiment, the organic compound having the
structure of Chemical Formula 1 may have a benzo-naphthyridine
moiety. For example, one of X.sub.1 to X.sub.4 in Chemical Formula
1 may be nitrogen atom and the rest of X.sub.1 to X.sub.4 may be
CR.sub.4. In an alternative embodiment, Y.sub.1 in Chemical Formula
1 may be nitrogen atom or an unsubstituted carbon atom and each of
Y.sub.2 to Y.sub.5 may independently be an unsubstituted or
substituted carbon atom. As an example, an organic compound having
the benzo-naphthyridine moiety may have the following structure of
Chemical Formula 2:
##STR00003##
In Chemical Formula 2, each of R.sub.11 and R.sub.12 is
independently linear or branched C.sub.1-C.sub.20 alkyl group or
C.sub.6-C.sub.20 aryl group. Each of R.sub.13 and R.sub.14 is
independently protium, deuterium, tritium or linear or branched
C.sub.1-C.sub.20 alkyl group. o is id identical as defined in
Chemical Formula 1. p is an integer of 1 to 3. Each or R.sub.15 to
R.sub.18 is independently protium, deuterium, tritium, linear or
branched C.sub.1-C.sub.20 alkyl group or C.sub.10-C.sub.30 fused
hetero aryl group having at least one nitrogen atom (N) on a ring,
wherein the C.sub.10-C.sub.30 fused hetero aryl group is
unsubstituted or substituted a group selected from the group
consisting of linear or branched C.sub.1-C.sub.20 alkyl group,
C.sub.6-C.sub.30 aryl group, C.sub.4-C.sub.30 hetero aryl group,
C.sub.4-C.sub.30 aromatic or hetero aromatic amino group and
combination thereof, wherein at least one of R.sub.15 to R.sub.18
is C.sub.10-C.sub.30 fused hetero aryl group having at least one
nitrogen atom (N) on the ring, wherein the C.sub.10-C.sub.30 fused
hetero aryl group is unsubstituted or substituted a group selected
from the group consisting of linear or branched C.sub.1-C.sub.20
alkyl group, C.sub.6-C.sub.30 aryl group, C.sub.4-C.sub.30 hetero
aryl group, C.sub.4-C.sub.30 aromatic or hetero aromatic amino
group and combination thereof. Y is nitrogen atom (N) or CR.sub.19,
wherein R.sub.19 is protium, deuterium, tritium or linear or
branched C.sub.1-C.sub.20 alkyl group.
Particularly, the organic compound having the structure of Chemical
Formula 1 or 2 may include any one having the following structure
of Chemical Formula 3.
##STR00004## ##STR00005## ##STR00006## ##STR00007## ##STR00008##
##STR00009## ##STR00010## ##STR00011## ##STR00012## ##STR00013##
##STR00014## ##STR00015## ##STR00016## ##STR00017## ##STR00018##
##STR00019## ##STR00020## ##STR00021## ##STR00022## ##STR00023##
##STR00024## ##STR00025##
The organic compound having the structure of any one in Chemical
Formulae 1 to 3 includes the fused hetero aryl moiety, which has
the p-type property, and the aza-acridine moiety, which has the
n-type property, linked by an aromatic linker. The organic compound
having the structure of any one in Chemical Formulae 1 to 3 has
excellent thermal resistance property, high excited state singlet
and triplet energy levels and wide energy level bandgap (Eg)
between the HOMO energy level and the LUMO energy level. As an
example, when the organic compound is used together with a delayed
fluorescent material and optionally a fluorescent material in the
EML, it is possible to transfer exciton energy to the fluorescent
material without energy loss during the emission process.
In other words, the organic compound having the structure of any
one in Chemical Formulae 1 to 3 can be used as the host in the EML
of the OLED to enhance luminous efficiency. It is possible to
minimize exciton quenching owing to an interaction between the
exciton in the host and a peripheral polaron and to prevent the
luminous lifetime of the OLED being lowered due to
electro-oxidation and photo-oxidation. When the organic compound
having the structure of any one in Chemical Formulae 1 to 3 is used
as the host in the EML, the organic compound can transfer
efficiently exciton energy to the fluorescent material so that the
OLED may have enhanced luminous efficiency. In addition, since the
organic compound in the EML is not deteriorated by heat, the OLED
having a long luminous lifetime and excellent color purity can be
realized.
[Organic Light Emitting Diode and Device]
The organic compound having the structure of any one in Chemical
Formulae 1 to 6 has enhanced thermal resistance property and
luminous property. The organic compound having the structure of any
one in Chemical Formulae 1 to 6 may be applied to an emitting
material layer of an organic light emitting diode so as to
implement high color purity and enhance luminous efficiency of the
diode. The organic light emitting diode of the present disclosure
may be applied to an organic light emitting device such as an
organic light emitting display device and an organic light emitting
illumination device. An organic light emitting display device will
be explained. FIG. 1 is a schematic cross-sectional view of an
organic light emitting display device in accordance with an
exemplary embodiment of the present disclosure.
As illustrated in FIG. 1, the organic light emitting display device
100 includes a substrate 102, a thin-film transistor Tr on the
substrate 102, and an organic light emitting diode 200 connected to
the thin film transistor Tr.
The substrate 102 may include, but are not limited to, glass, thin
flexible material and/or polymer plastics. For example, the
flexible material may be selected from the group, but are not
limited to, polyimide (PI), polyethersulfone (PES),
polyethylenenaphthalate (PEN), polyethylene terephthalate (PET),
polycarbonate (PC) and combination thereof. The substrate 102, over
which the thin film transistor Tr and the organic light emitting
diode 200 are arranged, form an array substrate.
A buffer layer 104 may be disposed over the substrate 102, and the
thin film transistor Tr is disposed over the buffer layer 104. The
buffer layer 104 may be omitted.
A semiconductor layer 110 is disposed over the buffer layer 104. In
one exemplary embodiment, the semiconductor layer 110 may include,
but are not limited to, oxide semiconductor materials. In this
case, a light-shield pattern may be disposed under the
semiconductor layer 110, and the light-shield pattern can prevent
light from being incident toward the semiconductor layer 110, and
thereby, preventing the semiconductor layer 110 from being
deteriorated by the light. Alternatively, the semiconductor layer
110 may include, but are not limited to, polycrystalline silicon.
In this case, opposite edges of the semiconductor layer 110 may be
doped with impurities.
A gate insulating layer 120 formed of an insulating material is
disposed on the semiconductor layer 110. The gate insulating layer
120 may include, but are not limited to, an inorganic insulating
material such as silicon oxide (SiO.sub.x) or silicon nitride
(SiN.sub.x).
A gate electrode 130 made of a conductive material such as a metal
is disposed over the gate insulating layer 120 so as to correspond
to a center of the semiconductor layer 110. While the gate
insulating layer 120 is disposed over a whole area of the substrate
102 in FIG. 1, the gate insulating layer 120 may be patterned
identically as the gate electrode 130.
An interlayer insulating layer 140 formed of an insulating material
is disposed on the gate electrode 130 with covering over an entire
surface of the substrate 102. The interlayer insulating layer 140
may include, but are not limited to, an inorganic insulating
material such as silicon oxide (SiO.sub.x) or silicon nitride
(SiN.sub.x), or an organic insulating material such as
benzocyclobutene or photo-acryl.
The interlayer insulating layer 140 has first and second
semiconductor layer contact holes 142 and 144 that expose both
sides of the semiconductor layer 110. The first and second
semiconductor layer contact holes 142 and 144 are disposed over
opposite sides of the gate electrode 130 with spacing apart from
the gate electrode 130. The first and second semiconductor layer
contact holes 142 and 144 are formed within the gate insulating
layer 120 in FIG. 1. Alternatively, the first and second
semiconductor layer contact holes 142 and 144 are formed only
within the interlayer insulating layer 140 when the gate insulating
layer 120 is patterned identically as the gate electrode 130.
A source electrode 152 and a drain electrode 154, each of which is
made of a conductive material such as a metal, are disposed on the
interlayer insulating layer 140. The source electrode 152 and the
drain electrode 154 are spaced apart from each other with respect
to the gate electrode 130, and contact both sides of the
semiconductor layer 110 through the first and second semiconductor
layer contact holes 142 and 144, respectively.
The semiconductor layer 110, the gate electrode 130, the source
electrode 152 and the drain electrode 154 constitute the thin film
transistor Tr, which acts as a driving element. The thin film
transistor Tr in FIG. 1 has a coplanar structure in which the gate
electrode 130, the source electrode 152 and the drain electrode 154
are disposed over the semiconductor layer 110. Alternatively, the
thin film transistor Tr may have an inverted staggered structure in
which a gate electrode is disposed under a semiconductor layer and
a source and drain electrodes are disposed over the semiconductor
layer. In this case, the semiconductor layer may comprise amorphous
silicon.
Although not shown in FIG. 1, a gate line and a data line, which
cross each other to define a pixel region, and a switching element,
which is connected to the gate line and the data line is, may be
further formed in the pixel region. The switching element is
connected to the thin film transistor Tr, which is a driving
element. Besides, a power line is spaced apart in parallel from the
gate line or the data line, and the thin film transistor Tr may
further include a storage capacitor configured to constantly keep a
voltage of the gate electrode for one frame.
In addition, the organic light emitting display device 100 may
include a color filter for absorbing a part of the light emitted
from the organic light emitting diode 200. For example, the color
filter may absorb a light of specific wavelength such as red (R),
green (G) or blue (B). In this case, the organic light emitting
display device 100 can implement full-color through the color
filter.
For example, when the organic light emitting display device 100 is
a bottom-emission type, the color filter may be disposed on the
interlayer insulating layer 140 with corresponding to the organic
light emitting diode 200. Alternatively, when the organic light
emitting display device 100 is a top-emission type, the color
filter may be disposed over the organic light emitting diode 200,
that is, a second electrode 220.
A passivation layer 160 is disposed on the source and drain
electrodes 152 and 154 over the whole substrate 102. The
passivation layer 160 has a flat top surface and a drain contact
hole 162 that exposes the drain electrode 154 of the thin film
transistor Tr. While the drain contact hole 162 is disposed on the
second semiconductor layer contact hole 154, it may be spaced apart
from the second semiconductor layer contact hole 154.
The organic light emitting diode 200 includes a first electrode 210
that is disposed on the passivation layer 160 and connected to the
drain electrode 154 of the thin film transistor Tr. The organic
light emitting diode 200 further includes an emitting unit 230 as
an emission layer and a second electrode 220 each of which is
disposed sequentially on the first electrode 210.
The first electrode 210 is disposed in each pixel region. The first
electrode 210 may be an anode and include a conductive material
having a relatively high work function value. For example, the
first electrode 210 may include, but are not limited to, a
transparent conductive material such as indium tin oxide (ITO),
indium zinc oxide (IZO), indium tin zinc oxide (ITZO), tin oxide
(SnO), zinc oxide (ZnO), indium cerium oxide (ICO), aluminum doped
zinc oxide (AZO), and the likes.
In one exemplary embodiment, when the organic light emitting
display device 100 is a top-emission type, a reflective electrode
or a reflective layer may be disposed under the first electrode
210. For example, the reflective electrode or the reflective layer
may include, but are not limited to, aluminum-palladium-copper
(APC) alloy.
In addition, a bank layer 170 is disposed on the passivation layer
160 in order to cover edges of the first electrode 210. The bank
layer 170 exposes a center of the first electrode 210.
An emitting unit 230 is disposed on the first electrode 210. In one
exemplary embodiment, the emitting unit 230 may have a mono-layered
structure of an emitting material layer. Alternatively, the
emitting unit 230 may have a multiple-layered structure of a hole
injection layer, a hole transport layer, an electron blocking
layer, an emitting material layer, a hole blocking layer, an
electron transport layer and/or an electron injection layer (See,
FIGS. 2, 5, 7, 9 and 11). In one embodiment, the organic light
emitting diode 200 may have one emitting unit 230. Alternatively,
the organic light emitting diode 200 may have multiple emitting
units 230 to form a tandem structure. The emitting unit 230
includes an organic compound having the structure of any one in
Chemical Formulae 1 to 6. As an example, the organic compound
having the structure of any one in Chemical Formulae 1 to 6 may be
used a host of an emitting material layer which may further
includes at least one dopant.
The second electrode 220 is disposed over the substrate 102 above
which the emitting unit 230 is disposed. The second electrode 220
may be disposed over a whole display area and may include a
conductive material with a relatively low work function value
compared to the first electrode 210. The second electrode 220 may
be a cathode. For example, the second electrode 220 may include,
but are not limited to, aluminum (Al), magnesium (Mg), calcium
(Ca), silver (Ag), alloy thereof or combination thereof such as
aluminum-magnesium alloy (Al--Mg).
In addition, an encapsulation film 180 may be disposed over the
second electrode 220 in order to prevent outer moisture from
penetrating into the organic light emitting diode 200. The
encapsulation film 180 may have, but are not limited to, a
laminated structure of a first inorganic insulating film 182, an
organic insulating film 184 and a second inorganic insulating film
186.
The emitting unit 230 of the OLED 200 includes the organic compound
having the structure of any one in Chemical Formulae 1 to 6, as
described above. Since the organic compound has excellent thermal
resistant property and luminous property, the OLED 200 can enhance
its luminous efficiency and luminous lifetime and lower its driving
voltage so as to reduce its consumption power by applying the
organic compound having the structure of any one in Chemical
Formulae 1 to 6 into the emitting unit 230.
FIG. 2 is a schematic cross-sectional view illustrating an organic
light emitting diode having a single-layered EML in accordance with
an exemplary embodiment of the present disclosure. As illustrated
in FIG. 2, the organic light emitting diode (OLED) 300 in
accordance with the first embodiment of the present disclosure
includes first and second electrodes 310 and 320 facing each other,
an emitting unit 330 as an emission layer disposed between the
first and second electrodes 310 and 320. In one exemplary
embodiment, the emitting unit 330 includes a hole injection layer
(HIL) 340, a hole transport layer (HTL) 350, an emitting material
layer (EML) 360, an electron transport layer (ETL) 370 and an
electron injection layer (EIL) 380 each of which is laminated
sequentially from the first electrode 310. Alternatively, the
emitting unit 330 may further include a first exciton blocking
layer, i.e. an electron blocking layer (EBL) 355 disposed between
the HTL 350 and the EML 360 and/or a second exciton blocking layer,
i.e. a hole blocking layer (HBL) 375 disposed between the EML 360
and the ETL 370.
The first electrode 310 may be an anode that provides a hole into
the EML 360. The first electrode 310 may include, but are not
limited to, a conductive material having a relatively high work
function value, for example, a transparent conductive oxide (TCO).
In an exemplary embodiment, the first electrode 310 may include,
but are not limited to, ITO, IZO, ITZO, SnO, ZnO, ICO, AZO, and the
likes.
The second electrode 320 may be a cathode that provides an electron
into the EML 360. The second electrode 320 may include, but are not
limited to, a conductive material having a relatively low work
function values, i.e., a highly reflective material such as Al, Mg,
Ca, Ag, alloy thereof, combination thereof, and the likes.
The HIL 340 is disposed between the first electrode 310 and the HTL
350 and improves an interface property between the inorganic first
electrode 310 and the organic HTL 350. In one exemplary embodiment,
the HIL 340 may include, but are not limited to,
4,4',4''-Tris(3-methylphenylamino)triphenylamine (MTDATA),
4,4',4''-Tris(N,N-diphenyl-amino)triphenylamine (NATA),
4,4',4''-Tris(N-(naphthalene-1-yl)-N-phenyl-amino)triphenylamine
(1T-NATA),
4,4',4''-Tris(N-(naphthalene-2-yl)-N-phenyl-amino)triphenylamine
(2T-NATA), Copper phthalocyanine (CuPc),
Tris(4-carbazoyl-9-yl-phenyl)amine (TCTA),
N,N'-Diphenyl-N,N'-bis(1-naphthyl)-1,1'-biphenyl-4,4''-diamine
(NPB; NPD), 1,4,5,8,9,11-Hexaazatriphenylenehexacarbonitrile
(Dipyrazino[2,3-f:2'3'-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile;
HAT-CN), 1,3,5-tris[4-(diphenylamino)phenyl]benzene (TDAPB),
poly(3,4-ethylenedioxythiphene)polystyrene sulfonate (PEDOT/PSS)
and/or
N-(biphenyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-
-fluoren-2-amine. The HIL 340 may be omitted in compliance with a
structure of the OLED 300.
The HTL 350 is disposed adjacently to the EML 360 between the first
electrode 310 and the EML 360. In one exemplary embodiment, the HTL
350 may include, but are not limited to,
N,N'-Diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine
(TPD), NPB, 4,4'-bis(N-carbazolyl)-1,1'-biphenyl (CBP),
Poly[N,N'-bis(4-butylpnehyl)-N,N'-bis(phenyl)-benzidine]
(Poly-TPD),
Poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphe-
nylamine))] (TFB), Di-[4-(N,N-di-p-tolyl-amino)-phenyl]cyclohexane
(TAPC),
N-(biphenyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-
-fluoren-2-amine and/or
N-(biphenyl-4-yl)-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)biphenyl-4-amine-
.
In one exemplary embodiment, each of the HIL 340 and the HTL 350
may be laminated with a thickness of, but are not limited to, about
5 to about 200 nm, and preferably about 5 to about 100 nm.
The EML 360 may include a host doped with a dopant. In this
exemplary embodiment, the EML 360 may include a host (a first host)
doped with a dopant (a first dopant). For example, the organic
compound having the structure of any one in Chemical Formulae 1 to
6 may be used as the host in the EML 360. The EML 360 may emit
light of red color, green color or blue color. The configuration
and energy levels among the luminous materials will be explained in
more detail.
The ETL 370 and the EIL 380 are laminated sequentially between the
EML 360 and the second electrode 320. The ETL 370 may include a
material having high electron mobility so as to provide electrons
stably with the EML 360 by fast electron transportation.
In one exemplary embodiment, the ETL 370 may include, but are not
limited to, oxadiazole-based compounds, triazole-based compounds,
phenanthroline-based compounds, benzoxazole-based compounds,
benzothiazole-based compounds, benzimidazole-based compounds,
triazine-based compounds, and the likes.
As an example, the ETL 370 may include, but are not limited to,
tris-(8-hydroxyquinoline aluminum (Alq.sub.3),
2-biphenyl-4-yl-5-(4-t-butylphenyl)-1,3,4-oxadiazole (PBD),
spiro-PBD, lithium quinolate (Liq),
1,3,5-Tris(N-phenylbenzimidazol-2-yl)benzene (TPBi),
Bis(2-methyl-8-quinolinolato-N1,O8)-(1,1'-biphenyl-4-olato)alumin-
um (BAlq), 4,7-diphenyl-1,10-phenanthroline (Bphen),
2,9-Bis(naphthalene-2-yl)4,7-diphenyl-1,10-phenanthroline (NBphen),
2,9-Dimethyl-4,7-diphenyl-1,10-phenathroline (BCP),
3-(4-Biphenyl)-4-phenyl-5-tert-butylphenyl-1,2,4-triazole (TAZ),
4-(Naphthalen-1-yl)-3,5-diphenyl-4H-1,2,4-triazole (NTAZ),
1,3,5-Tri(p-pyrid-3-yl-phenyl)benzene (TpPyPB),
2,4,6-Tris(3'-(pyridin-3-yl)biphenyl-3-yl) 1,3,5-triazine
(TmPPPyTz),
Poly[9,9-bis(3'-(N,N-dimethyl)-N-ethylammonium)-propyl)-2,7-fluorene]-alt-
-2,7-(9,9-dioctylfluorene)](PFNBr) and/or tris(phenylquinoxaline)
(TPQ).
The EIL 380 is disposed between the second electrode 320 and the
ETL 370, and can improve physical properties of the second
electrode 320 and therefore, can enhance the life span of the OLED
300. In one exemplary embodiment, the EIL 380 may include, but are
not limited to, an alkali halide and/or an alkali earth halide such
as LiF, CsF, NaF, BaF.sub.2 and the likes, and/or an organic metal
compound such as lithium benzoate, sodium stearate, and the
likes.
As an example, each of the ETL 370 and the EIL 380 may be laminated
with a thickness of, but are not limited to, about 10 to about 100
nm.
When holes are transferred to the second electrode 320 via the EML
360 and/or electrons are transferred to the first electrode 310 via
the EML 360, the luminous lifetime and the luminous efficiency of
the OLED 300 may be reduced. In order to prevent those phenomena,
the OLED 300 in accordance with this embodiment of the present
disclosure has at least one exciton blocking layer disposed
adjacently to the EML 360.
For example, the OLED 300 of the exemplary embodiment includes the
EBL 355 between the HTL 350 and the EML 360 so that electrons
cannot be transferred from the EML 360 to the HTL 350. In one
exemplary embodiment, the EBL 355 may include, but are not limited
to, TCTA, Tris[4-(diethylamino)phenyl]amine,
N-(biphenyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-
-fluorene-2-amine, TAPC, MTDATA, 1,3-bis(carbazol-9-yl)benzene
(mCP), 3,3'-bis(N-carbazolyl)-1,1'-biphenyl (mCBP), CuPc,
N,N'-bis[4-(bis(3-methylphenyl)amino)phenyl]-N,N'-diphenyl-[1,1'-biphenyl-
]-4,4'-diamine (DNTPD), TDAPB,
2,8-bis(9-phenyl-9H-carbazol-3-yl)dibenzo[b,d]thiophene, and/or
3,6-bis(N-carbazolyl)-N-phenyl-carbazole.
In addition, the OLED 300 further includes the HBL 375 as a second
exciton blocking layer between the EML 360 and the ETL 370 so that
holes cannot be transferred from the EML 360 to the ETL 370. In one
exemplary embodiment, the HBL 375 may include, but are not limited
to, oxadiazole-based compounds, triazole-based compounds,
phenanthroline-based compounds, benzoxazole-based compounds,
benzothiazole-based compounds, benzimidazole-based compounds, and
triazine-based compounds.
For example, the HBL 375 may include a compound having a relatively
low HOMO energy level compared to the emitting material in EML 360.
The HBL 375 may include, but are not limited to, BCP, BAlq,
Alq.sub.3, PBD, spiro-PBD, Liq,
Bis-4,5-(3,5-di-3-pyridylphenyl)-2-methylpyrimidine (B3PYMPM),
DPEPO, 9-(6-(9H-carbazol-9-yl)pyridine-3-yl)-9H-3,9'-bicarbazole
and combination thereof.
As described schematically above, the EML 360 of the OLED 300 in
accordance with the first embodiment of the present disclosure
include a host, i.e. the organic compound having the structure of
any one in Chemical Formulae 1 to 6, and a dopant having a delayed
fluorescent property (T dopant). When the EML 360 includes the
dopant having the delayed fluorescent property, the OLED 300 can
improve its luminous efficiency and its luminous lifetime and lower
its driving voltage.
An Organic Light Emitting Diode (OLED) emits light as holes
injected from the anode and electrons injected from the cathode are
combined to form excitons in EML and then unstable excited state
excitons return to a stable ground state. Theoretically, when
electrons meet holes to form exciton, a singlet exciton of a paired
spin and a triplet exciton of an unpaired spin are produced by a
ratio of 1:3 by spin arrangements. Only the singlet exciton among
the excitons can be involved in emission process in case of
fluorescent materials. Accordingly, the OLED may exhibit luminous
efficiency by maximum 5% in case of using the common fluorescent
material.
In contrast, phosphorescent materials use different luminous
mechanism of converting both singlet excitons and triplet exciton
into light. The phosphorescent materials can convert singlet
excitons into triplet excitons through intersystem crossing (ISC).
Therefore, it is possible to enhance luminous efficiency in case of
applying the phosphorescent materials that use both the singlet
excitons and the triplet excitons during the luminous process
compared to the fluorescent materials. However, prior art blue
phosphorescent materials exhibit too low color purity to apply with
the display device and exhibit very short luminous lifetime, and
therefore, they have not been used in commercial display
devices.
A delayed fluorescent material, which can solve the limitations
accompanied by the prior art fluorescent dopants and the
phosphorescent dopants, has been developed recently. Representative
delayed fluorescent material is a thermally-activated delayed
fluorescent (TADF) material. Since the delayed fluorescent material
generally has both an electron donor moiety and an electron
acceptor moiety within its molecular structure, it can be converted
to an intramolecular charge transfer (ICT) state. In case of using
the delayed fluorescent material as a dopant, it is possible to use
both the excitons of singlet energy level S.sub.1 and the excitons
of triplet energy level T.sub.1 during the emission process.
The luminous mechanism of the delayed fluorescent material will be
explained with referring to FIG. 3, which is a schematic diagram
illustrating a luminous mechanism of the delayed fluorescent
material in an EML in accordance with another exemplary embodiment
of the present disclosure. As illustrated in FIG. 3, both the
excitons of singlet energy level S.sub.1.sup.TD and the excitons of
triplet energy level T.sub.1.sup.TD in the delayed fluorescent
material can move to an intermediate energy level state, i.e. ICT
state, and then the intermediate stated excitons can be transferred
to a ground state (S.sub.0; S.sub.1.fwdarw.ICT.rarw.T.sub.1). Since
the excitons of singlet energy level S.sub.1.sup.TD as well as the
excitons of triplet energy level T.sub.1.sup.TD in the delayed
fluorescent material is involved in the emission process, the
delayed fluorescent material can improve luminous efficiency.
Because both the HOMO and the LUMO are widely distributed over the
whole molecule within the common fluorescent material, it is not
possible to inter-convert between the singlet energy level and the
triplet energy level within it (selection rule). In contrast, since
the delayed fluorescent material, which can be converted to ICT
state, has little orbital overlaps between HOMO and LUMO, there is
little interaction between the HOMO state molecular orbital and the
LUMO state molecular orbital in the state where dipole moment is
polarized within the delayed fluorescent material. As a result, the
changes of spin states of electrons does not have an influence on
other electrons, and a new charge transfer band (CT band) that does
not follow the selection rule is formed in the delayed fluorescent
material.
In other words, since the delayed fluorescent material has the
electron acceptor moiety spacing apart from the electron donor
moiety within the molecule, it exists as a polarized state having a
large dipole moment within the molecule. As the interaction between
HOMO molecular orbital and LUMO molecular orbital becomes little in
the state where the dipole moment is polarized, both the triplet
energy level excitons and the singlet energy level excitons can be
converted to ICT state. Accordingly, the excitons of triplet energy
level T.sub.1 as well as the excitons of singlet energy level
S.sub.1 can be involved in the emission process.
In case of driving the diode that includes the delayed fluorescent
material, 25% excitons of singlet energy level S.sub.1.sup.TD and
75% excitons of triplet energy level T.sub.1.sup.TD are converted
to ICT state by heat or electrical field, and then the converted
excitons transfer to the ground state S.sub.0 with luminescence.
Therefore, the delayed fluorescent material may have 100% internal
quantum efficiency in theory.
The delayed fluorescent material must have an energy level bandgap
.DELTA.E.sub.ST.sup.TD equal to or less than about 0.3 eV, for
example, from about 0.05 to about 0.3 eV, between the singlet
energy level S.sub.1.sup.TD and the triplet energy level
T.sub.1.sup.TD so that exciton energy in both the singlet energy
level and the triplet energy level can be transferred to the ICT
state. The material having little energy level bandgap between the
singlet energy level S.sub.1.sup.TD and the triplet energy level
T.sub.1.sup.TD can exhibit common fluorescence with Inter system
Crossing (ISC) in which the excitons of singlet energy level
S.sub.1.sup.TD can be transferred to the excitons of triplet energy
level T.sub.1.sup.TD, as well as delayed fluorescence with Reverser
Inter System Crossing (RISC) in which the excitons of triplet
energy level T.sub.1.sup.TD can be transferred upwardly to the
excitons of singlet energy level S.sub.1.sup.TD, and then the
exciton of singlet energy level S.sub.1.sup.TD transferred from the
triplet energy level T.sub.1.sup.TD can be transferred to the
ground state S.sub.0.
The delayed fluorescent material can realize identical quantum
efficiency as the prior art phosphorescent material including heavy
metal because the delayed fluorescent material can obtain luminous
efficiency up to 100% in theory. The host for implementing the
delayed fluorescence can induce triplet exciton energy generated at
the delayed fluorescent material to be involved in the luminous
process without quenching as a non-emission. In order to induce
such exciton energy transfer, energy levels among the host and the
delayed fluorescent material should be adjusted.
FIG. 4 is a schematic diagram illustrating luminous mechanism by
energy level bandgap between luminous materials in accordance with
an exemplary embodiment of the present disclosure. As illustrated
schematically in FIG. 4, an excited state singlet energy level
S.sub.1.sup.H and an excited state triplet energy level
T.sub.1.sup.H of the host should be higher than an excited state
singlet energy level S.sub.1.sup.TD and an excited state triple
energy level T.sub.1.sup.TD of the dopant having the delayed
fluorescent property, respectively. For example, the excited
triplet energy level T.sub.1.sup.H of the host may be higher than
the excited state triplet energy level T.sub.1.sup.TD of the dopant
by at least about 0.2 eV.
As an example, when the excited state triplet energy level
T.sub.1.sup.H of the host is not higher enough than the excited
state triplet energy levels T.sub.1.sup.TD of the dopant, which may
be a delayed fluorescent material, the excitons of the triplet
energy level T.sub.1.sup.TD of the dopant can be reversely
transferred to the excited state triplet energy level T.sub.1.sup.H
of the host, which cannot utilize triplet exciton energy.
Accordingly, the excitons of the triplet energy level
T.sub.1.sup.TD of the dopant having the delayed fluorescent
property may be quenched as a non-emission and the triplet state
excitons of the dopant cannot be involved in the emission.
The dopant (TD) must have an energy level bandgap
.DELTA.E.sub.ST.sup.TD between the excited state singlet energy
level S.sub.1.sup.TD and the excited state triplet energy level
T.sub.1.sup.TD equal to or less than about 0.3 eV, for example
between about 0.05 and about 0.3 eV, in order to realize delayed
fluorescence (See, FIG. 3).
In addition, it is necessary to adjust properly HOMO energy levels
and LUMO energy levels of the host and the dopant, which may be the
fluorescent material. For example, it is preferable that an energy
level bandgap (|HOMO.sup.H-HOMO.sup.TD|) between a HOMO energy
level (HOMO.sup.H) of the host and a HOMO energy level
(HOMO.sup.TD) of the dopant, or an energy level bandgap
(|LUMO.sup.H-LUMO.sup.TD|) between a LUMO energy level (LUMO.sup.H)
of the host and a LUMO energy level (LUMO.sup.TD) of the dopant may
be equal to or less than about 0.5 eV, for example, between about
0.1 eV to about 0.5 eV. In this case, the charges can be
transported efficiently from the host to the first dopant and
thereby enhancing an ultimate luminous efficiency.
Moreover, an energy level bandgap (Eg.sup.H) between the HOMO
energy level (HOMO.sup.H) and the LUMO energy level (LUMO.sup.H) of
the host may be larger than an energy level bandgap (Eg.sup.TD)
between the HOMO energy level (HOMO.sup.TD) and the LUMO energy
level (LUMO.sup.TD) of the dopant. As an example, the HOMO energy
level (HOMO.sup.H) of the host is deeper or lower than the HOMO
energy level (HOMO.sup.TD) of the dopant, and the LUMO energy level
(LUMO.sup.H) of the host is shallower or higher than the LUMO
energy level (LUMO.sup.TD) of the dopant.
The organic compound having the structure of any one in Chemical
Formulae 1 to 6 includes the carbazolyl moiety having p-type
property, and the second dibenzofuranyl/dibenzothiophenyl moiety
having n-type property, and the carbazolyl moiety and the second
dibenzofuranyl/dibenzothiophenyl moiety are linked to the first
dibenzofuranyl/dibenzothiophenyl moiety asymmetrically. The organic
compound having the structure of any one in Chemical Formulae 1 to
6 may exhibit more amorphous property so as to improve extremely
its heat resistance. Accordingly, the crystallization caused by
Joule's heat in driving the OLED is prevented, and the structure of
the OLED is not destroyed. Moreover, because the organic compound
having the structure of any one in Chemical Formulae 1 to 6
includes the carbazolyl moiety and dibenzofuranyl/dibenzothiophenyl
moieties, each of which includes two benzene rings, the organic
compound has a HOMO energy level and a LUMO energy level proper for
use as the host in the EML 360. Particularly, when the organic
compound is used together with a delayed fluorescent material and
optionally a fluorescent material in the EML, it is possible to
transfer exciton energy to the fluorescent material without energy
loss during the emission process.
In other words, when the organic compound having the structure of
any one in Chemical Formulae 1 to 6 is used as the host in the EML
360 of the OLED 300, it is possible to minimize exciton quenching
owing to an interaction between the exciton in the host and a
peripheral polaron and to prevent the luminous lifetime of the OLED
being lowered due to electro-oxidation and photo-oxidation. Also,
the organic compound has excellent thermal resistance property and
high triplet energy level and large energy level bandgap between
the HOMO energy level and the LUMO energy level. When the organic
compound having the structure of any one in Chemical Formulae 1 to
6 is used as the host in the EML 360, the OLED 300 can enhance its
luminous efficiency due to efficient exciton energy transfer from
the host to the dopant. In addition, the OLED 300 can realize high
color purity and long luminous lifetime as the damage to the
luminous materials in the EML 360 is reduced.
In one exemplary embodiment, when the organic compound having the
structure of any one in Chemical Formulae 1 to 6 is used as the
host in the EML 360, a delayed fluorescent material having proper
energy levels compared to the host may be used as the dopant in the
EML 360. For example, the dopant may emit light of red color, green
color or blue color. As an example, the dopant may have an excited
state singlet energy level (S.sub.1.sup.TD), but are not limited
to, between about 2.7 eV and about 2.75 eV and an excited state
triplet energy level (T.sub.1.sup.TD), but are not limited to,
between about 2.4 eV and about 2.5 eV in order to implement
luminescence level applicable to a display device.
Delayed fluorescent materials, which can be used as the dopant, may
have the HOMO energy level (HOMO.sup.TD), but are not limited to,
between about -5.0 eV and about -6.0 eV, and preferably between
about -5.0 eV and about -5.5 eV, the LUMO energy level
(LUMO.sup.TD), but are not limited to, between about -2.5 eV and
about -3.5 eV, and preferably between about -2.5 eV and about -3.0
eV, and the energy level bandgap (Eg.sup.TD) between those HOMO and
LUMO energy levels (HOMO.sup.TD and LUMO.sup.TD) may be, but are
not limited to, between about 2.2 eV and about 3.0 eV, and
preferably between about 2.4 eV and about 2.8 eV. The organic
compound having the structure of any one in Chemical Formulae 1 to
6 may have the HOMO energy level (HOMO.sup.H), but are not limited
to, between about -5.0 eV and about -6.5 eV, and preferably between
about -5.5 eV and about -6.2 eV, the LUMO energy level
(LUMO.sup.H), but are not limited to, between about -1.5 eV and
about -3.0 eV, and preferably between about -1.5 eV and about -2.5
eV, and the energy level bandgap (Eg.sup.H) between those HOMO and
LUMO energy levels (HOMO.sup.H and LUMO.sup.H) may be, but are not
limited to, between about 3.0 eV and about 4.0 eV, and preferably
between about 3.0 eV and about 3.5 eV.
In one exemplary embodiment, a delayed fluorescent material that
can be used as the dopant in the EML 360 may include any one having
the following structure of Chemical 7.
##STR00026## ##STR00027## ##STR00028## ##STR00029## ##STR00030##
##STR00031## ##STR00032## ##STR00033## ##STR00034## ##STR00035##
##STR00036## ##STR00037## ##STR00038## ##STR00039## ##STR00040##
##STR00041##
In another exemplary embodiment, the dopant as a delayed
fluorescent material in the EML 360 may include, but are not
limited to,
10-(4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-9,9-dimethyl-9,10-dihydroa-
cridine (DMAC-TRZ),
10,10'-(4,4'-sulfonylbis(4,1-phenylene))bis(9,9-dimethyl-9,10-dihydroacri-
dine) (DMAC-DPS),
10-phenyl-10H,10'H-spiro[acridine-9,9'-anthracen]-10'-one (ACRSA),
3,6-dibenzoyl-4,5-di(1-methyl-9-phenyl-9H-carbazoyl)-2-ethynylbenzonitril-
e (Cz-VPN),
9,9',9''-(5-(4,6-diphenyl-1,3,5-triazin-2-yl)benzene-1,2,3-triyl)
tris(9H-carbazole) (TcZTrz),
9,9'-(5-(4,6-diphenyl-1,3,5-triazin-2-yl)-1,3-phenylene)bis(9H-carbazole)
(DczTrz), 9,9',9'',
9'''-((6-phenyl-1,3,5-triazin-2,4-diyl)bis(benzene-5,3,1-triyl))tetrakis(-
9H-carbazole) (DDczTrz),
bis(4-(9H-3,9'-bicarbazol-9-yl)phenyl)methanone (CC2BP),
9'-[4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-3,3'',6,6''-tetra-
phenyl-9,3': 6',9''-ter-9H-carbazole (BDPCC-TPTA),
9'-[4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9,3':,6',9''-ter-9H-carbaz-
ole (BCC-TPTA),
9,9'-(4,4'-sulfonylbis(4,1-phenylene))bis(3,6-dimethoxy-9H-carbazole)
(DMOC-DPS),
9-(4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-3',6'-diphenyl-9H-3,9'-bica-
rbazole (DPCC-TPTA),
10-(4,6-diphenyl-1,3,5-triazin-2-yl)-10H-phenoxazine (Phen-TRZ),
9-(4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-9H-carbazole
(Cab-Ph-TRZ),
1,2,3,5-Tetrakis(3,6-carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN),
2,3,4,6-tetra(9H-carbazol-9-yl)-5-fluorobenzonitrile (4CZFCN),
10-(4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-10H-spiro[acridine-9,9'-xa-
nthene] and/or
10-(4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-10H-spiro[acridine-9,9'-fl-
uorene] (SpiroAC-TRZ).
When the EML 360 includes the host and the dopant having the
delayed fluorescent property, the EML 360 may include the dopant of
about 1 to about 70% by weight, preferably of about 10 to about 50%
by weight, and more preferably of about 20 to about 50% by weight.
The EML 360 may be laminated with a thickness of, but are not
limited to, about 10 to about 200 nm, preferably about 20 to about
100 nm, and more preferably about 30 to about 50 nm.
In the above first embodiment, the EML 360 includes only one dopant
having the delayed fluorescent property. Unlike that embodiment,
the EML may include plural dopants having different luminous
properties. FIG. 5 is a schematic cross-sectional view illustrating
an organic light emitting diode in accordance with another
exemplary embodiment of the present disclosure. As illustrated in
FIG. 5, the OLED 300A according to the second embodiment of the
present disclosure includes first and second electrodes 310 and 320
facing each other and an emitting unit 330a disposed between the
first and second electrodes 310 and 320.
In one exemplary embodiment, the emitting unit 330a as an emission
layer includes a HIL 340, a HTL 350, an EML 360a, an ETL 370 and an
ETL 380 each of which is laminated sequentially over the first
electrode 310. Alternatively, the emitting unit 330a may further
include a first exciton blocking layer, i.e. an EBL 355 disposed
between the HTL 350 and the EML 360a and/or a second exciton
blocking layer, i.e. a HBL 375 disposed between the EML 360a and
the ETL 370. The emitting unit 330a may have the same
configurations and materials as the emitting unit 330 in FIG. 2
except the EML 360a.
The EML 360a may include a host (a first host), a first dopant and
a second dopant. The first dopant may be a delayed fluorescent
dopant (T dopant; TD) and the second dopant may be a fluorescent
dopant (F dopant; FD). In this case, the organic compound having
the structure of any one in Chemical Formulae 1 to 6 may be used as
the host. When the EML 360a includes the delayed fluorescent dopant
and the fluorescent dopant, the OLED 300A can implement
hyper-fluorescence enhancing its luminous efficiency by adjusting
energy levels among the luminous materials, i.e. the host and the
dopants.
When an EML includes only the dopant which has the delayed
fluorescent property and has the structure of any one in Chemical
Formula 7, the EML may implement high internal quantum efficiency
as the prior art phosphorescent materials including heavy metals
because the dopant can exhibit 100% internal quantum efficiency in
theory. However, because of the bond formation between the electron
acceptor and the electron donor and sterical twists within the
delayed fluorescent material, additional charge transfer transition
(CT transition) is caused thereby, so that the delayed fluorescent
materials show emission spectra having very broad FWHM in the
course of emission, which results in poor color purity. In
addition, delayed fluorescent material utilizes the triplet exciton
energy as well as the singlet exciton energy in the luminous
process with rotating each moiety within its molecular structure,
which results in twisted internal charge transfer (TICT). As a
result, a luminous lifetime of an OLED including only the delayed
fluorescent materials may be reduced owing to weakening of
molecular bonding forces among the delayed fluorescent
materials.
In the second embodiment, the EML 360a further includes the second
dopant, which may be a fluorescent or phosphorescent material, in
order to prevent the color purity and luminous lifetime from being
reduced in case of using only the delayed fluorescent materials.
The triplet exciton energy of the first dopant (T dopant), which
may be the delayed fluorescent material, is converted to the
singlet exciton energy of its own by RISC mechanism, then the
converted singlet exciton energy of the first dopant can be
transferred to the second dopant (F dopant), which may be the
fluorescent or phosphorescent material, in the same EML 360a by
Dexter energy transfer mechanism, which transfer exciton energies
depending upon wave function overlaps among adjacent molecules by
inter-molecular electron exchanges and exciton diffusions.
When the EML 360a includes the host which is the organic compound
having the structure of any one in Chemical Formulae 1 to 6, the
first dopant (T dopant) which may be the organic compound having
the structure of any one in Chemical Formula 7 and having the
delayed fluorescent property and the second dopant (F dopant) which
may be the fluorescent or phosphorescent material, it is necessary
to adjust properly energy levels amount those luminous
materials.
FIG. 6 is a schematic diagram illustrating luminous mechanism by
energy level bandgap among luminous materials in accordance with
another exemplary embodiment of the present disclosure. An energy
level bandgap between an excited state singlet energy level
S.sub.1.sup.TD and an excited state triplet energy level
T.sub.1.sup.TD of the first dopant (T dopant) may be equal to or
less than about 0.3 eV in order to realize the delayed
fluorescence. In addition, an excited state singlet energy level
S.sub.1.sup.H and an excited state triplet energy level
T.sub.1.sup.H of the host is higher than the excited state singlet
energy level S.sub.1.sup.TD and the excited state triplet energy
level T.sub.1.sup.TD of the first dopant, respectively. As an
example, the excited state triplet energy level T.sub.1.sup.H of
the host may be higher than the excited state triplet energy level
T.sub.1.sup.TD of the first dopant by at least about 0.2 eV.
Moreover, the excited state triplet energy level T.sub.1.sup.TD of
the first dopant is higher than an excited state triplet energy
level T.sub.1.sup.FD of the second dopant. In one exemplary
embodiment, the excited state singlet energy level S.sub.1.sup.TD
of the first dopant may be higher than an excited state singlet
energy level S.sub.1.sup.FD of the second dopant as a fluorescent
material.
In addition, an energy level bandgap (|HOMO.sup.H-HOMO.sup.TD|)
between a HOMO energy level (HOMO.sup.H) of the host and a HOMO
energy level (HOMO.sup.TD) of the first dopant, or an energy level
bandgap (|LUMO.sup.H-LUMO.sup.TD|) between a LUMO energy level
(LUMO.sup.H) of the host and a LUMO energy level (LUMO.sup.TD) of
the first dopant may be equal to or less than about 0.5 eV.
For example, the host may include the organic compound having the
structure of any one in Chemical Formulae 1 to 6 and the first
dopant may include, but are not limited to, the organic compound
having the structure of any one in Chemical Formula 7.
Alternatively, the second dopant may include, but are not limited
to, DMAC-TRZ, DMAC-DPS, ACRSA, Cz-VPN, TcZTrz, DczTrz, DDczTrz,
CC2BP, BDPCC-TPTA, BCC-TPTA, DMOC-DPS, DPCC-TPTA, Phen-TRZ,
Cab-Ph-TRZ, 4CzIPN, 4CZFCN,
10-(4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-10H-spiro[acridine-9,9'-xa-
nthene] and/or SpiroAC-TRZ.
The exciton energy should be effectively transferred from the first
dopant as the delayed fluorescent material to the second dopant as
the fluorescent or phosphorescent material in order to implement
hyper-fluorescence. With regard to energy transfer efficiency from
the delayed fluorescent material to the fluorescent or
phosphorescent material, an overlap between an emission spectrum of
the delayed fluorescent material and an absorption spectrum of the
fluorescent or phosphorescent material can be considered. As an
example, a fluorescent or phosphorescent material having an
absorption spectrum with overlapping area with an emission spectrum
of the first dopant may be used as the second dopant in order to
transfer exciton energy efficiently from the first dopant to the
second dopant.
In one exemplary embodiment, the fluorescent material as the second
dopant may have, but are not limited to, quinolino-acridine core.
As an example, the second dopant having the quinolino-acridine core
may include 5,12-dimethylquinolino[2,3-b]acridine-7,14(5H,
12H)-dione(S.sub.1: 2.3 eV; T.sub.1: 2.0 eV; LUMO: -3.0 eV; HOMO:
-5.4 eV), 5,12-diethylquinolino[2,3-b]acridine-7,14(5H,
12H)-dione(S.sub.1: 2.3 eV; T.sub.1: 2.2 eV; LUMO: -3.0 eV; HOMO:
-5.4 eV),
5,12-dibutyl-3,10-difluoroquinolino[2,3-b]acridine-7,14(5H,
12H)-dione(S.sub.1: 2.2 eV; T.sub.1: 2.0 eV; LUMO: -3.1 eV; HOMO:
-5.5 eV),
5,12-dibutyl-3,10-bis(trifluoromethyl)quinolino[2,3-b]acridine-7,14(-
5H, 12H)-dione(S.sub.1: 2.2 eV; T.sub.1: 2.0 eV; LUMO: -3.1 eV;
HOMO: -5.5 eV),
5,12-dibutyl-2,3,9,10-tetrafluoroquinolino[2,3-b]acridine-7,14(5H,
12H)-dione(S.sub.1: 2.0 eV; T.sub.1: 1.8 eV; LUMO: -3.3 eV; HOMO:
-5.5 eV).
In addition, the fluorescent material as the second dopant may
include, but are not limited to,
1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)eth-
enyl]-4H-pyran-4-ylidene}propanedinitrile(DCJTB; S.sub.1: 2.3 eV;
T.sub.1: 1.9 eV; LUMO: -3.1 eV; HOMO: -5.3 eV). Moreover, metal
complexes which can emit light of red, green or blue color may be
used as the second dopant.
In one exemplary embodiment, the weight ratio of the host may be
larger than the weight ratio of the first and second dopants in the
EML 360a, and the weight ratio of the first dopant may be larger
than the weight ratio of the second dopant. In an alternative
embodiment, the weight ratio of the host is larger than the weight
ratio of the first dopant and the weight ratio of the first dopant
is larger than the weight ratio of the second dopant. When the
weight ratio of the first dopant is larger than the weight ratio of
the second dopant, exciton energy can be transferred efficiently
from the first dopant to the second dopant by a Dexter energy
transfer mechanism. As an example, the EML 360a includes the host
of about 60 to about 75% by weight, the first dopant of about 20 to
about 40% by weight and the second dopant of about 0.1 to about 5%
by weight.
The OLEDs in accordance with the previous embodiments have a
single-layered EML. Alternatively, an OLED in accordance with the
present disclosure may include multiple-layered EML. FIG. 7 is a
schematic cross-sectional view illustrating an organic light
emitting diode having a double-layered EML in accordance with
another exemplary embodiment of the present disclosure.
As illustrated in FIG. 7, the OLED 400 in accordance with an
exemplary third embodiment of the present disclosure includes first
and second electrodes 410 and 420 facing each other and an emitting
unit 430 as an emission layer disposed between the first and second
electrodes 410 and 420.
In one exemplary embodiment, the emitting unit 430 includes an HIL
440, an HTL 450, and EML 460, an ETL 470 and an EIL 480 each of
which is laminated sequentially over the first electrode 410. In
addition, the emitting unit 430 may further include an EBL 455 as a
first exciton blocking layer disposed between the HTL 450 and the
EML 460, and/or an HBL 475 as a second exciton blocking layer
disposed between the EML 460 and the ETL 470.
As described above, the first electrode 410 may be an anode and may
include, but are not limited to, a conductive material having a
relatively large work function values such as ITO, IZO, SnO, ZnO,
ICO, AZO, and the likes. The second electrode 420 may be a cathode
and may include, but are not limited to, a conductive material
having a relatively small work function values such as Al, Mg, Ca,
Ag, alloy thereof or combination thereof.
The HIL 440 is disposed between the first electrode 410 and the HTL
450. The HIL 440 may include, but are not limited to, MTDATA, NATA,
1T-NATA, 2T-NATA, CuPc, TCTA, NPB(NPD), HAT-CN, TDAPB, PEDOT/PSS
and/or
N-(biphenyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-
-fluoren-2-amine. The HIL 440 may be omitted in compliance with the
structure of the OLED 400.
The HTL 450 is disposed adjacently to the EML 460 between the first
electrode 410 and the EML 460. The HTL 450 may include, but are not
limited to, aromatic amine compounds such as TPD, NPD(NPB), CBP,
poly-TPD, TFB, TAPC,
N-(biphenyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-
-fluoren-2-amine and/or
N-(biphenyl-4-yl)-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)biphenyl-4-amine-
.
The EML 460 includes a first EML (EML1) 462 and a second EML (EML2)
464. The EML1 462 is disposed between the EBL 455 and the HBL 475
and the EML2 464 is disposed between the EML1 462 and the HBL 475.
One of the EML1 462 and the EML2 464 includes a first dopant (T
dopant) having a delayed fluorescent property, for example, an
organic compound having the structure of any one in Chemical
Formula 7, the other of the EML1 462 and the EML2 464 includes a
second dopant as a fluorescent or phosphorescent material. The
configuration and energy levels among the luminous materials in the
EML 460 will be explained in more detail below.
The ETL 470 is disposed between the EML 460 and the EIL 480. In one
exemplary embodiment, the ETL 470 may include, but are not limited
to, oxadiazole-based compounds, triazole-based compounds,
phenanthroline-based compounds, benzoxazole-based compounds,
benzothiazole-based compounds, benzimidazole-based compounds,
triazine-based compounds, and the likes. As an example, the ETL 470
may include, but are not limited to, Alq.sub.3, PBD, spiro-PBD,
Liq, TPBi, BAlq, Bphen, NBphen, BCP, TAZ, NTAZ, TpPyPB, TmPPPyTz,
PFNBr and/or TPQ.
The EIL 480 is disposed between the second electrode 420 and the
ETL 470. In one exemplary embodiment, the EIL 480 may include, but
are not limited to, an alkali halide and/or an alkali earth halide
such as LiF, CsF, NaF, BaF.sub.2 and the likes, and/or an organic
metal compound such as lithium benzoate, sodium stearate, and the
likes.
The EBL 455 is disposed between the HTL 450 and the EML 460 for
controlling and preventing electron transportations between the HTL
450 and the EML 460. As an example, The EBL 455 may include, but
are not limited to, TCTA, Tris[4-(diethylamino)phenyl]amine,
N-(biphenyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-
-fluorene-2-amine, TAPC, MTDATA, mCP, mCBP, CuPc, DNTPD, TDAPB,
2,8-bis(9-phenyl-9H-carbazol-3-yl)dibenzo[b,d]thiophene and/or
3,6-bis(N-carbazolyl)-N-phenyl-carbazole.
The HBL 475 is disposed between the EML 460 and the ETL 470 for
preventing hole transportations between the EML 460 and the ETL
470. In one exemplary embodiment, the HBL 475 may include, but are
not limited to, oxadiazole-based compounds, triazole-based
compounds, phenanthroline-based compounds, benzoxazole-based
compounds, benzothiazole-based compounds, benzimidazole-based
compounds, and triazine-based compounds. As an example, the HBL 475
may include a compound having a relatively low HOMO energy level
compared to the emitting material in EML 460. The HBL 475 may
include, but are not limited to, BCP, BAlq, Alq.sub.3, PBD,
spiro-PBD, Liq, B3PYMPM, DPEPO,
9-(6-(9H-carbazol-9-yl)pyridine-3-yl)-9H-3,9'-bicarbazole and
combination thereof.
In the exemplary third embodiment, the EML1 462 includes a first
host and a first dopant, which is a delayed fluorescent material
and the EML2 464 includes a second host and a second dopant, which
is a fluorescent or phosphorescent material.
The EML1 462 includes the first host which is the organic compound
having the structure of any one in Chemical Formulae 1 to 6 and the
first dopant which is the delayed fluorescent material. An energy
level bandgap (.DELTA.E.sub.ST.sup.TD) between the excited state
singlet energy level S.sub.1.sup.TD and the excited state triplet
energy level T.sub.1.sup.TD of the first dopant is very small
(.DELTA.E.sub.ST.sup.TD is equal to or less than about 0.3 eV; See,
FIG. 3) so that triplet exciton energy of the first dopant can be
transferred to the singlet exciton energy of its own by RISC
mechanism. While the first dopant has high internal quantum
efficiency, but it has poor color purity due to its wide FWHM
(full-width half maximum).
On the contrary, the EML2 464 may include the second host and the
second dopant as a fluorescent material. While the second dopant as
a fluorescent material has advantage of high color purity due to
its narrow FWHM, but its internal quantum efficiency is low because
its triplet exciton cannot be involved in a luminous process.
However, in this exemplary embodiment, the singlet exciton energy
and the triplet exciton energy of the first dopant, which has the
delayed fluorescent property, in the EML1 462 can be transferred to
the second dopant, which may be the fluorescent or phosphorescent
material, in the EML2 464 disposed adjacently to the EML1 462 by
FRET (Forster resonance energy transfer) mechanism, which transfers
energy non-radially through electrical fields by dipole-dipole
interactions. Accordingly, the ultimate emission occurs in the
second dopant within the EML2 464.
In other words, the triplet exciton energy of the first dopant is
converted to the singlet exciton energy of its own in the EML1 462
by RISC mechanism. Then, the converted singlet exciton energy of
the first dopant is transferred to the singlet exciton energy of
the second dopant because the excited state singlet energy level
S.sub.1.sup.TD of the first dopant is higher than the excited state
singlet energy level S.sub.1.sup.FD of the second dopant (See, FIG.
8). The second dopant in the EML2 464 can emit light using the
triplet exciton energy as well as the singlet exciton energy.
As the exciton energy, which is generated at the first dopant as
the delayed fluorescent material in the EML1 462, is transferred
from the first dopant to the second dopant in the EML2 464, a
hyper-fluorescence can be realized. In this case, the first dopant
only acts as transferring energy to the second dopant. Substantial
light emission is occurred in the EML2 464 including the second
dopant which is the fluorescent or phosphorescent dopant and has a
narrow FWHM. Accordingly, the OLED 400 can enhance its quantum
efficiency and improve its color purity due to narrow FWHM.
Each of the EML1 462 and the EML2 464 includes the first host and
the second host, respectively. The exciton energies generated at
the first and second hosts should be transferred to the first
dopant as the delayed fluorescent material to emit light. It is
necessary to adjust energy levels among the luminous materials in
order to realize a hyper-fluorescence. FIG. 8 is a schematic
diagram illustrating luminous mechanism by energy level bandgap
among luminous materials in accordance with another exemplary
embodiment of the present disclosure.
As illustrated in FIG. 8, excited state singlet energy levels
S.sub.1.sup.H1 and S.sub.1.sup.H2 and excited state triplet energy
levels T.sub.1.sup.H1 and T.sub.1.sup.H2 of the first and second
hosts should be higher than the excited state singlet energy level
S.sub.1.sup.TD and the excited state triplet energy level
T.sub.1.sup.TD of the first dopant as the delayed fluorescent
material, respectively.
For example, when each of the excited state triplet energy levels
T.sub.1.sup.H1 and T.sub.1.sup.H2 of the first and second hosts is
not high enough than the excited state triplet energy level
T.sub.1.sup.TD of the first dopant, the triplet exciton of the
first dopant may be reversely transferred to the excited state
triplet energy levels T.sub.1.sup.H1 and T.sub.1.sup.H2 of the
first and second hosts, which cannot utilize triplet exciton
energy. Accordingly, the excitons of the triplet energy level
T.sub.1.sup.TD of the first dopant may be quenched as a
non-emission and the triplet state excitons of the first dopant
cannot be involved in the emission. As an example, each of the
excited state triplet energy levels T.sub.1.sup.H1 and
T.sub.1.sup.H2 of the first and second hosts may be higher than the
excited state triplet energy level T.sub.1.sup.TD of the first
dopant by at least about 0.2 eV.
The excited state singlet energy level S.sub.1.sup.H2 of the second
host is higher than an excited state singlet energy level
S.sub.1.sup.FD of the second dopant. In this case, the singlet
exciton energy generated at the second host can be transferred to
the excited singlet energy level S.sub.1.sup.FD of the second
dopant.
In addition, it is necessary for the EML 460 to implement high
luminous efficiency and color purity as well as to transfer exciton
energy efficiently from the first dopant, which is converted to ICT
complex state by RISC mechanism in the EML1 462, to the second
dopant which is the fluorescent or phosphorescent material in the
EML2 464. In order to realize such an OLED 400, the excited state
triplet energy level T.sub.1.sup.TD of the first dopant is higher
than an excited state triplet energy level T.sub.1.sup.FD of the
second dopant. In one exemplary embodiment, the excited state
singlet energy level S.sub.1.sup.TD of the first dopant may be
higher than an excited state singlet energy level S.sub.1.sup.FD of
the second dopant as a fluorescent material.
In one exemplary embodiment, the energy level bandgap between the
excited state singlet energy level S.sub.1.sup.TD and the excited
state triplet energy level T.sub.1.sup.TD of the first dopant may
be equal to or less than about 0.3 eV. In addition, an energy level
bandgap (|HOMO.sup.H-HOMO.sup.TD|) between a HOMO energy level
(HOMO.sup.H) of the first and/or second hosts and a HOMO energy
level (HOMO.sup.TD) of the first dopant, or an energy level bandgap
(|LUMO.sup.H-LUMO.sup.TD|) between a LUMO energy level (LUMO.sup.H)
of the first and/or second hosts and a LUMO energy level
(LUMO.sup.TD) of the first dopant may be equal to or less than
about 0.5 eV.
When the luminous materials do not satisfy the required energy
levels as described above, exciton energies are quenched at the
first and second dopants or exciton energies cannot transferred
efficiently from the host to the dopants, so that OLED 400 may have
reduced quantum efficiency.
The first host and the second host may be the same or different
from each other. For example, each of the first host and the second
host may independently include the organic compound having the
structure of any one in Chemical Formulae 1 to 6. In one exemplary
embodiment, the first dopant may include, but are not limited to,
the organic compound having the structure of any one in Chemical
Formula 7. In an alternative embodiment, the second dopant may
include, but are not limited to, DMAC-TRZ, DMAC-DPS, ACRSA, Cz-VPN,
TcZTrz, DczTrz, DDczTrz, CC2BP, BDPCC-TPTA, BCC-TPTA, DMOC-DPS,
DPCC-TPTA, Phen-TRZ, Cab-Ph-TRZ, 4CzIPN, 4CZFCN,
10-(4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-10H-spiro[acridine-
-9,9'-xanthene] and/or SpiroAC-TRZ.
The second dopant may have narrow FWHM and have luminous spectrum
having large overlapping area with the absorption spectrum of the
first dopant. As an example, the second dopant may include, but are
not limited to, an organic compound having a quinolino-acridine
core such as 5,12-dimethylquinolino[2,3-b]acridine-7,14(5H,
12H)-dione, 5,12-diethylquinolino[2,3-b]acridine-7,14(5H,
12H)-dione,
5,12-dibutyl-3,10-difluoroquinolino[2,3-b]acridine-7,14(5H,
12H)-dione,
5,12-dibutyl-3,10-bis(trifluoromethyl)quinolino[2,3-b]acridine-7,14(5H,
12H)-dione,
5,12-dibutyl-2,3,9,10-tetrafluoroquinolino[2,3-b]acridine-7,14(5H,
12H)-dione, DCJTB and any metal complexes which can emit light of
red, green or blue color.
In one exemplary embodiment, each of the first and second hosts in
the EML1 462 or the EML2 464 may have more weight ratio than the
first dopant and the second dopant in the same EMLs 462 and 464,
respectively. In addition, the weight ratio of the first dopant in
the EML1 462 may be larger than the weight ratio of the second
dopant in the EML2 464. In this case, it is possible to transfer
enough energy from the first dopant in the EML1 462 to the second
dopant in the EML2 464.
As an example, the EML1 462 may include the first dopant of, but
are not limited to, about 1 to about 70% by weigh, preferably about
10 to about 50% by weight, and preferably about 20 to about 50% by
weight.
The weight ratio of the second host may be larger than the weight
ratio of the second dopant in the EML2 464. As an example, the EML2
464 may include the second host, but are not limited to, about 90
to about 99% by weight, and preferably about 95 to about 99% by
weight, and the second dopant, but are not limited to, about 1 to
about 10% by weight, and preferably about 1 to about 5% by
weight.
Each of the EML1 462 and the EML2 464 may be laminated with a
thickness of, but are not limited to, about 5 to about 100 nm,
preferably about 10 to about 30 nm, and more preferably about 10 to
about 20 nm.
When the EML2 464 is disposed adjacently to the HBL 475 in one
exemplary embodiment, the second host, which is included in the
EML2 464 together with the second dopant, may be the same material
as the HBL 475. In this case, the EML2 464 may have a hole blocking
function as well as an emission function. In other words, the EML2
464 can act as a buffer layer for blocking holes. In one
embodiment, the HBL 475 may be omitted where the EML2 464 may be a
hole blocking layer as well as an emitting material layer.
When the EML2 464 is disposed adjacently to the EBL 455 in another
exemplary embodiment, the second host may be the same material as
the EBL 455. In this case, the EML2 464 may have an electron
blocking function as well as an emission function. In other words,
the EML2 464 can act as a buffer layer for blocking electrons. In
one embodiment, the EBL 455 may be omitted where the EML2 464 may
be an electron blocking layer as well as an emitting material
layer.
An OLED having a triple-layered EML will be explained. FIG. 9 is a
schematic cross-sectional view illustrating an organic light
emitting diode having a triple-layered EML in accordance with
another exemplary embodiment of the present disclosure.
As illustrated in FIG. 9, an OLED 500 in accordance with the fourth
embodiment of the present disclosure includes first and second
electrodes 510 and 520 facing each other and an emitting unit 530
as an emission layer disposed between the first and second
electrodes 510 and 520.
In one exemplary embodiment, the emitting unit 530 includes an HIL
540, an HTL 550, and EML 560, an ETL 570 and an EIL 580 each of
which is laminated sequentially over the first electrode 510. In
addition, the emitting unit 530 may further include an EBL 555 as a
first exciton blocking layer disposed between the HTL 550 and the
EML 560, and/or an HBL 575 as a second exciton blocking layer
disposed between the EML 560 and the ETL 570.
As described above, the first electrode 510 may be an anode and may
include, but are not limited to, a conductive material having a
relatively large work function values such as ITO, IZO, SnO, ZnO,
ICO, AZO, and the likes. The second electrode 520 may be a cathode
and may include, but are not limited to, a conductive material
having a relatively small work function values such as Al, Mg, Ca,
Ag, alloy thereof or combination thereof.
The HIL 540 is disposed between the first electrode 510 and the HTL
550. The HIL 540 may include, but are not limited to, MTDATA, NATA,
1T-NATA, 2T-NATA, CuPc, TCTA, NPB(NPD), HAT-CN, TDAPB, PEDOT/PSS
and/or
N-(biphenyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-
-fluoren-2-amine. The HIL 540 may be omitted in compliance with the
structure of the OLED 500.
The HTL 550 is disposed adjacently to the EML 560 between the first
electrode 510 and the EML 560. The HTL 550 may include, but are not
limited to, aromatic amine compounds such as TPD, NPD(NPB), CBP,
poly-TPD, TFB, TAPC,
N-(biphenyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-
-fluoren-2-amine and/or
N-(biphenyl-4-yl)-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)biphenyl-4-amine-
.
The EML 560 includes a first EML (EML1) 562, a second EML (EML2)
564 and a third EML (EML3) 566. The EML1 562 is disposed between
the EBL 555 and the HBL 575, the EML2 564 is disposed between the
EBL 555 and the EML1 562 and the EML3 566 is disposed between the
EML1 562 and the HBL 575. The configuration and energy levels among
the luminous materials in the EML 560 will be explained in more
detail below.
The ETL 570 is disposed between the EML 560 and the EIL 580. In one
exemplary embodiment, the ETL 570 may include, but are not limited
to, oxadiazole-based compounds, triazole-based compounds,
phenanthroline-based compounds, benzoxazole-based compounds,
benzothiazole-based compounds, benzimidazole-based compounds,
triazine-based compounds, and the likes. As an example, the ETL 570
may include, but are not limited to, Alq.sub.3, PBD, spiro-PBD,
Liq, TPBi, BAlq, Bphen, NBphen, BCP, TAZ, NTAZ, TpPyPB, TmPPPyTz,
PFNBr and/or TPQ.
The EIL 580 is disposed between the second electrode 520 and the
ETL 570. In one exemplary embodiment, the EIL 580 may include, but
are not limited to, an alkali halide and/or an alkali earth halide
such as LiF, CsF, NaF, BaF.sub.2 and the likes, and/or an organic
metal compound such as lithium benzoate, sodium stearate, and the
likes.
The EBL 555 is disposed between the HTL 550 and the EML 560 for
controlling and preventing electron transportations between the HTL
550 and the EML 560. As an example, The EBL 555 may include, but
are not limited to, TCTA, Tris[4-(diethylamino)phenyl]amine,
N-(bipnehyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-
-fluorene-2-amine, TAPC, MTDATA, mCP, mCBP, CuPc, DNTPD, TDAPB,
2,8-bis(9-phenyl-9H-carbazol-3-yl)dibenzo[b,d]thiophene and/or
3,6-bis(N-carbazolyl)-N-phenyl-carbazole.
The HBL 575 is disposed between the EML 560 and the ETL 570 for
preventing hole transportations between the EML 560 and the ETL
570. In one exemplary embodiment, the HBL 575 may include, but are
not limited to, oxadiazole-based compounds, triazole-based
compounds, phenanthroline-based compounds, benzoxazole-based
compounds, benzothiazole-based compounds, benzimidazole-based
compounds, and triazine-based compounds. As an example, the HBL 575
may include a compound having a relatively low HOMO energy level
compared to the emitting material in EML 560. The HBL 575 may
include, but are not limited to, BCP, BAlq, Alq.sub.3, PBD,
spiro-PBD, Liq, B3PYMPM, DPEPO,
9-(6-(9H-carbazol-9-yl)pyridine-3-yl)-9H-3,9'-bicarbazole and
combination thereof.
The EML1 562 includes a first dopant (T dopant) having a delayed
fluorescent property. Each of the EML2 564 and the EML3 566
includes a second dopant (a first fluorescent or phosphorescent
dopant, F dopant 1) and a third dopant (a second fluorescent or
phosphorescent dopant). Each of the EML1 562, EML2 564 and EML3 566
further includes a first host, a second host and a third host,
respectively.
In accordance with this embodiment, the singlet energy as well as
the triplet energy of the first dopant, which is the delayed
fluorescent material, in the EML1 562 can be transferred to the
second and third dopants (the first and second fluorescent or
phosphorescent dopants) each of which is included in the EML2 564
and EML3 566 disposed adjacently to the EML1 562 by FRET energy
transfer mechanism. Accordingly, the ultimate emission occurs in
the second and third dopants in the EML2 564 and the EML3 566.
In other words, the triplet exciton energy of the first dopant is
converted to the singlet exciton energy of its own in the EML1 562
by RISC mechanism, then the singlet exciton energy of the first
dopant is transferred to the singlet exciton energy of the second
and third dopants because the excited state singlet energy level
S.sub.1.sup.TD of the first dopant is higher than the excited state
singlet energy levels S.sub.1.sup.FD1 and S.sub.1.sup.FD2 of the
second and third dopants (See, FIG. 10). The singlet exciton energy
of the first dopant in the EML1 562 is transferred to the second
and third dopants in the EML2 564 and the EML3 566 which is
disposed adjacently to the EML1 562 by FRET mechanism.
The second and third dopants in the EML2 564 and EML3 566 can emit
light using the singlet exciton energy and the triplet exciton
energy derived from the first dopant. Each of the second and third
dopants may have narrower FWHM compared to the first dopant. As the
exciton energy, which is generated at the first dopant as the
delayed fluorescent material in the EML1 562, is transferred to the
second and third dopants in the EML2 564 and the EML3 566, a
hyper-fluorescence can be realized. In this case, the first dopant
only acts as transferring energy to the second and third dopants.
The EML1 562 including the first dopant is not involved in the
ultimate emission process. Substantial light emission is occurred
in the EML2 564 and in the EML3 566 each of which includes the
second dopant and the third dopant with a narrow FWHM. Accordingly,
the OLED 500 can enhance its quantum efficiency and improve its
color purity due to narrow FWHM. As an example, each of the second
and third dopants may have an emission wavelength range having a
large overlapping area with an absorption wavelength range of the
first dopant.
In this case, it is necessary to adjust properly energy levels
among the hosts and the dopants in the EML1 562, the EML2 564 and
the EML3 566. FIG. 10 is a schematic diagram illustrating luminous
mechanism by energy level bandgap among luminous materials in
accordance with another exemplary embodiment of the present
disclosure.
As illustrated in FIG. 10, excited state singlet energy levels
S.sub.1.sup.H1, S.sub.1.sup.H2 and S.sub.1.sup.H3 and excited state
triplet energy levels T.sub.1.sup.H1, T.sub.1.sup.H2 and
T.sub.1.sup.H3 of the first to third hosts should be higher than
the excited state singlet energy level S.sub.1.sup.TD and the
excited state triplet energy level T.sub.1.sup.TD of the first
dopant as the delayed fluorescent material, respectively.
For example, when each of the excited triplet energy levels
T.sub.1.sup.H1, T.sub.1.sup.H2 and T.sub.1.sup.H3 of the first to
third hosts is not high enough than the excited state triplet
energy level T.sub.1.sup.TD of the first dopant, the triplet
exciton of the first dopant may be reversely transferred to the
excited state triplet energy levels T.sub.1.sup.H1, T.sub.1.sup.H2
and T.sub.1.sup.H3 of the first to third hosts, which cannot
utilize triplet exciton energy. Accordingly, the excitons of the
triplet energy level T.sub.1.sup.TD of the first dopant may be
quenched as a non-emission and the triplet state excitons of the
first dopant cannot be involved in the emission. As an example,
each of the excited state triplet energy levels T.sub.1.sup.H1,
T.sub.1.sup.H2 and T.sub.1.sup.H3 of the first to third hosts may
be higher than the excited state triplet energy level
T.sub.1.sup.TD of the first dopant by at least about 0.2 eV.
In addition, it is necessary for the EML 560 to implement high
luminous efficiency and color purity as well as to transfer exciton
energy efficiently from the first dopant, which is converted to ICT
complex state by RISC mechanism in the EML1 562, to the second and
third dopants each of which is the fluorescent or phosphorescent
material in the EML2 564 and the EML3 566. In order to realize such
an OLED 500, the excited state triplet energy level T.sub.1.sup.TD
of the first dopant in the EML1 562 is higher than each of excited
state triplet energy levels T.sub.1.sup.FD1 and T.sub.1.sup.FD2 of
the second and third dopants. In one exemplary embodiment, the
excited state singlet energy level S.sub.1.sup.TD of the first
dopant may be higher than each of excited state singlet energy
levels S.sub.1.sup.FD1 and S.sub.1.sup.FD2 of the second and third
dopants as fluorescent material.
Moreover, the exciton energy, which is transferred from the first
dopant to each of the second and third dopants, should not be
transferred to the second and third hosts in order to realize
efficient light emission. As an example, each of the excited
singlet energy levels S.sub.1.sup.H2 and S.sub.1.sup.H3 of the
second and third hosts may be higher than each of the excited state
singlet energy level S.sub.1.sup.FD1 and S.sub.1.sup.FD2 of the
second and third dopants, respectively. In one exemplary
embodiment, the energy level bandgap between the excited state
singlet energy level S.sub.1.sup.TD and the excited state triplet
energy level T.sub.1.sup.TD of the first dopant may be equal to or
less than about 0.3 eV in order to implement a delayed
fluorescence.
In addition, an energy level bandgap (|HOMO.sup.H-HOMO.sup.TD|)
between a HOMO energy level (HOMO.sup.H) of the first to third
hosts and a HOMO energy level (HOMO.sup.TD) of the first dopant, or
an energy level bandgap (|LUMO.sup.H-LUMO.sup.TD|) between a LUMO
energy level (LUMO.sup.H) of the first to third hosts and a LUMO
energy level (LUMO.sup.TD) of the first dopant may be equal to or
less than about 0.5 eV.
Each of the EML1 562, the EML2 564 and the EML3 566 may include the
first host, the second host and the third host, respectively. For
example, each of the first to third hosts may be the same or
different from each other. For Example, each of the first to third
hosts may independently include the organic compound having the
structure of any one in Chemical Formulae 1 to 6. In one exemplary
embodiment, the first dopant may include, but are not limited to,
the organic compound having the structure of any one in Chemical
Formula 7. In an alternative embodiment, the first dopant may
include, but are not limited to, DMAC-TRZ, DMAC-DPS, ACRSA, Cz-VPN,
TcZTrz, DczTrz, DDczTrz, CC2BP, BDPCC-TPTA, BCC-TPTA, DMOC-DPS,
DPCC-TPTA, Phen-TRZ, Cab-Ph-TRZ, 4CzIPN, 4CZFCN,
10-(4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-10H-spiro[acridine-9,9'-xa-
nthene] and/or SpiroAC-TRZ.
Each of the second and third dopants may have narrow FWHM and have
luminous spectrum having large overlapping area with the absorption
spectrum of the first dopant. As an example, each of the second and
third dopants may independently include, but are not limited to, an
organic compound having a quinolino-acridine core such as
5,12-dimethylquinolino[2,3-b]acridine-7,14(5H, 12H)-dione,
12-diethylquinolino[2,3-b]acridine-7,14(5H, 12H)-dione,
5,12-dibutyl-3,10-difluoroquinolino[2,3-b]acridine-7,14(5H,
12H)-dione,
5,12-dibutyl-3,10-bis(trifluoromethyl)quinolino[2,3-b]acridine-7,14(5H,
12H)-dione,
5,12-dibutyl-2,3,9,10-tetrafluoroquinolino[2,3-b]acridine-7,14(5H,
12H)-dione, DCJTB and any metal complexes which can emit light of
red, green or blue color.
In one exemplary embodiment, each of the second and third hosts in
the EML2 564 and the EML3 566 may have weigh ratio equal to or more
than the weight ratio of the second and third dopants within the
same EMLs. The weight ratio of the first dopant in the EML1 562 may
be more than the weight ratio of the second and third dopants in
the EML2 564 and the EML3 566. In this case, it is possible to
transfer enough exciton energy from the first dopant in the EML1
562 to the second and third dopants in the EML2 564 and the EML3
566 through FRET energy transfer mechanism.
As an example, the EML1 562 may include the first dopant of about 1
to about 70% by weight, preferably about 10 to about 50% by weight,
and more preferably about 20 to about 50% by weight. Each weight
ratio of the second and thirds hosts may be larger than each weight
ratio of the second and third dopants in the EML2 564 and the EML3
566. As an example, each of the EML2 564 and EML3 566 may include
the second or third host, but are not limited to, about 90 to about
99% by weight, and preferably about 95 to about 99% by weight, and
the second or third dopant, but are not limited to, about 1 to
about 10% by weight, and preferably about 1 to about 5% by
weight.
The EML1 562 may be laminated with a thickness of, but are not
limited to, about 2 to about 100 nm, preferably about 2 to about 30
nm, and preferably about 2 to about 20 nm. Each of the EML2 564 and
the EML3 566 may be laminated with a thickness of, but are not
limited to, about 5 to about 100 nm, preferably about 10 to about
30 nm, and more preferably about 10 to about 20 nm.
When the EML2 564 is disposed adjacently to the EBL 555 in one
exemplary embodiment, the second host, which is included in the
EML2 564 together with the second dopant, may be the same material
as the EBL 555. In this case, the EML2 564 may have an electron
blocking function as well as an emission function. In other words,
the EML2 564 can act as a buffer layer for blocking electrons. In
one embodiment, the EBL 555 may be omitted where the EML2 564 may
be an electron blocking layer as well as an emitting material
layer.
When the EML3 566 is disposed adjacently to the HBL 575 in another
exemplary embodiment, the third host, which is included in the EML3
566 together with the third dopant, may be the same material as the
HBL 575. In this case, the EML3 566 may have a hole blocking
function as well as an emission function. In other words, the EML3
566 can act as a buffer layer for blocking holes. In one
embodiment, the HBL 575 may be omitted where the EML3 566 may be a
hole blocking layer as well as an emitting material layer.
In still another exemplary embodiment, the second host in the EML2
564 may be the same material as the EBL 555 and the third host in
the EML3 566 may be the same material as the HBL 575. In this
embodiment, the EML2 564 may have an electron blocking function as
well as an emission function, and the EML3 566 may have a hole
blocking function as well as an emission function. In other words,
each of the EML2 564 and the EML3 566 can act as a buffer layer for
blocking electrons or hole, respectively. In one embodiment, the
EBL 555 and the HBL 575 may be omitted where the EML2 564 may be an
electron blocking layer as well as an emitting layer and the EML3
566 may be a hole blocking layer as well as an emitting material
layer.
In the above embodiments, the OLED having only one emitting unit is
described. Unlike the above embodiment, the OLED may have multiple
emitting units so as to form a tandem structure. FIG. 11 is a
cross-sectional view illustrating an organic light emitting diode
in accordance with still another embodiment of the present
disclosure.
As illustrated in FIG. 11, the OLED 600 in accordance with the
fifth embodiment of the present disclosure includes first and
second electrodes 610 and 620 facing each other, a first emitting
unit 630 as a first emission layer disposed between the first and
second electrodes 610 and 620, a second emitting unit 730 as a
second emission layer disposed between the first emitting unit 630
and the second electrode 620, and a charge generation layer 710
disposed between the first and second emitting units 630 and
730.
As mentioned above, the first electrode 610 may be an anode and
include, but are not limited to, a conductive material having a
relatively large work function values. As an example, the first
electrode 610 may include, but are not limited to, ITO, IZO, SnO,
ZnO, ICO, AZO, and the likes. The second electrode 620 may be a
cathode and may include, but are not limited to, a conductive
material having a relatively small work function values such as Al,
Mg, Ca, Ag, alloy thereof or combination thereof. Each of the first
and second electrodes 610 and 620 may be laminated with a thickness
of, but are not limited to, about 30 to about 300 nm.
The first emitting unit 630 includes a HIL 640, a first HTL (a
lower HTL) 650, a lower EML 660 and a first ETL (a lower ETL) 670.
The first emitting unit 630 may further include a first EBL (a
lower EBL) 655 disposed between the first HTL 650 and the lower EML
660 and/or a first HBL (a lower HBL) 675 disposed between the lower
EML 660 and the first ETL 670.
The second emitting unit 730 includes a second HTL (an upper HTL)
750, an upper EML 760, a second ETL (an upper ETL) 770 and an EIL
780. The second emitting unit 730 may further include a second EBL
(an upper EBL) 755 disposed between the second HTL 750 and the
upper EML 760 and/or a second HBL (an upper HBL) 775 disposed
between the upper EML 760 and the second ETL 770.
At least one of the lower EML 660 and the upper EML 760 may include
the organic compound having the structure of any one in Chemical
Formulae 1 to 6 and emit green (G) light. As an example, one of the
lower and upper EMLs 660 and 760 may emit green (G) light, and the
other of the lower and upper EMLs 660 and 760 may emit blue (B)
and/or red (R) light. Alternatively, one of the lower and upper
EMLs 660 and 760 may emit blue (B) light and the other of the lower
and upper EMLs 660 and 760 may emit green (G), red (R), red-green
(RG) or yellow-green (YG). Hereinafter, the OLED 600, where the
lower EML 660 emits green light and includes the organic compound
having the structure of any one in Chemical Formulae 1 to 6 and the
upper EML 760 emits blue and/or red lights, will be explained.
The HIL 640 is disposed between the first electrode 610 and the
first HTL 650 and improves an interface property between the
inorganic first electrode 610 and the organic first HTL 650. In one
exemplary embodiment, the HIL 640 may include, but are not limited
to, MTDATA, NATA, 1T-NATA, 2T-NATA, CuPc, TCTA, NPB(NPD), HAT-CN,
TDAPB, PEDOT/PSS and/or
N-(biphenyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-
-fluoren-2-amine. The HIL 640 may be omitted in compliance with a
structure of the OLED 600.
Each of the first and second HTLs 650 and 750 may independently
include, but are not limited to, TPD, NPD(NPB), CBP, poly-TPD, TFB,
TAPC,
N-(biphenyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-
-fluoren-2-amine and/or
N-(biphenyl-4-yl)-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)biphenyl-4-amine-
. Each of the HIL 640 and the first and second HTLs 650 and 750 may
be laminated with a thickness of, but are not limited to, about 5
to about 200 nm, and preferably about 5 to about 100 nm.
Each of the first and second ETLs 670 and 770 facilitates electron
transportations in the first emitting unit 630 and the second
emitting unit 730, respectively. Each of the first and second ETLs
670 and 770 may independently include, but are not limited to,
oxadiazole-based compounds, triazole-based compounds,
phenanthroline-based compounds, benzoxazole-based compounds,
benzothiazole-based compounds, benzimidazole-based compounds,
triazine-based compounds, and the likes, respectively. As an
example, each of the first and second ETLs 670 and 770 may
independently include, but are not limited to, Alq.sub.3, PBD,
spiro-PBD, Liq, TPBi, BAlq, Bphen, NBphen, BCP, TAZ, NTAZ, TpPyPB,
TmPPPyTz, PFNBr and/or TPQ, respectively.
The EIL 780 is disposed between the second electrode 620 and the
second ETL 770, and can improve physical properties of the second
electrode 620 and therefore, can enhance the life span of the OLED
600. In one exemplary embodiment, the EIL 780 may include, but are
not limited to, an alkali halide and/or an alkali earth halide such
as LiF, CsF, NaF, BaF.sub.2 and the likes, and/or an organic metal
compound such as lithium benzoate, sodium stearate, and the
likes.
As an example, each of the first and second EBLs 655 and 755 may
independently include, but are not limited to, TCTA,
Tris[4-(diethylamino)phenyl]amine,
N-(bipnehyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-
-fluorene-2-amine, TAPC, MTDATA, mCP, mCBP, CuPc, DNTPD, TDAPB,
2,8-bis(9-phenyl-9H-carbazol-3-yl)dibenzo[b,d]thiophene and/or
3,6-bis(N-carbazolyl)-N-phenyl-carbazole, respectively.
Each of the first and second HBLs 675 and 775 may independently
include, but are not limited to, oxadiazole-based compounds,
triazole-based compounds, phenanthroline-based compounds,
benzoxazole-based compounds, benzothiazole-based compounds,
benzimidazole-based compounds, and triazine-based compounds. As an
example, each of the first and second HBLs 675 and 775 may
independently include, but are not limited to, BCP, BAlq,
Alq.sub.3, PBD, spiro-PBD, Liq, B3PYMPM, DPEPO,
9-(6-(9H-carbazol-9-yl)pyridine-3-yl)-9H-3,9'-bicarbazole and
combination thereof, respectively.
In one exemplary embodiment, when the upper EML 760 emits red
light, the upper EML 760 may be, but are not limited to a
phosphorescent material layer including a host such as CBP and the
likes and at least one dopant selected from the group consisting of
PIQIr(acac) (bis(1-phenylisoquinoline)acetylacetonate iridium),
PQIr(acac) (bis(1-phenylquinoline)acetylacetonate iridium), PQIr
(tris(1-phenylquinoline)iridium) and PtOEP(octaethylporphyrin
platinum). Alternatively, the upper EML 760 may be a fluorescent
material layer including PBD:Eu(DMB)3(phen), perylene and/or their
derivatives. In this case, the upper EML 760 may emit red light
having, but are not limited to, emission wavelength ranges of about
600 nm to about 650 nm.
In another exemplary embodiment, when the upper EML 760 emits blue
light, the upper EML 760 may be, but are not limited to, a
phosphorescent material layer including a host such as CBP and the
likes and at least one iridium-based dopant. Alternatively, the
upper EML 760 may be a fluorescent material layer including any one
selected from the group consisting of spiro-DPVBi, spiro-CBP,
distrylbenzene (DSB), distrylarylene (DSA), PFO-based polymers and
PPV-based polymers. The upper EML 760 may emit light of sky-blue
color or deep blue color as well as blue color. In this case, the
upper EML 760 may emit red light having, but are not limited to,
emission wavelength ranges of about 440 nm to about 480 nm.
In one exemplary embodiment, the second emitting unit 730 may have
double-layered EML 760, for example, a blue emitting material layer
and a red emitting material layer, in order to enhance luminous
efficiency of the red light. In this case, the upper EML 760 may
emit light having, but are not limited to, emission wavelength
ranges of about 440 nm to about 650 nm.
The charge generation layer (CGL) 710 is disposed between the first
emitting unit 630 and the second emitting unit 730. The CGL 710
include an N-type CGL 810 disposed adjacently to the first emitting
unit 630 and a P-type CGL 820 disposed adjacently to the second
emitting unit 730. The N-type CGL 810 injects electrons into the
first emitting unit 630 and the P-type CGL 820 injects holes into
the second emitting unit 730.
As an example, the N-type CGL 810 may be a layer doped with an
alkali metal such as Li, Na, K and/or Cs and/or an alkaline earth
metal such as Mg, Sr, Ba and/or Ra. For example, a host used in the
N-type CGL 810 may include, but are not limited to, an organic
compound such as Bphen or MTDATA. The alkali metal or the alkaline
earth metal may be doped by about 0.01 wt % to about 30 wt %.
The P-type CGL 820 may include, but are not limited to, an
inorganic material selected from the group consisting of tungsten
oxide (WO.sub.x), molybdenum oxide (MoO.sub.x), beryllium oxide
(Be.sub.2O.sub.3), vanadium oxide (V.sub.2O.sub.5) and combination
thereof, and/or an organic material selected from the group
consisting of NPD, HAT-CN,
2,3,5,6-Tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ), TPD,
N,N,N',N'-Tetranaphthalenyl-benzidine (TNB), TCTA,
N,N'-dioctyl-3,4,9,10-perylenedicarboximide (PTCDI-C8) and
combination thereof.
The lower EML 660 includes a first EML (EML1) 662 disposed between
the first EBL 655 and the first HBL 675, a second EML (EML2) 664
disposed between the first EBL 655 and the EML1 662 and a third EML
(EML3) 666 disposed between the EML1 662 and the first HBL 675. The
EML1 662 includes a first dopant (T dopant) which is a delayed
fluorescent material. Each of the EML2 664 and the EML3 666
includes a second dopant (a first F dopant) and a third dopant (a
second F dopant) each of which is a fluorescent or phosphorescent
material, respectively. Each of the EML1 662, the EML2 664 and the
EML3 666 includes a first host, a second host and a third host,
respectively.
In this case, the singlet exciton energy as well as the triplet
exciton energy of the first dopant in the EML1 662 can be
transferred to the second and third dopants each of which is
included in the EML2 664 and EML3 666 disposed adjacently to the
EML1 662 by FRET energy transfer mechanism. Accordingly, the
ultimate emission occurs in the second and third dopants in the
EML2 664 and the EML3 666.
In other words, the triplet exciton energy of the first dopant is
converted to the singlet exciton energy of its own in the EML1 662
by RISC mechanism, then the singlet exciton energy of the first
dopant is transferred to the singlet exciton energy of the second
and third dopants because the excited state singlet energy level
S.sub.1.sup.TD of the first fluorescent dopant is higher than each
of the excited state singlet energy levels S.sub.1.sup.FD1 and
S.sub.1.sup.FD2 of the second and third dopants (See, FIG. 10).
The second and third dopants in the EML2 664 and EML3 666 can emit
light using the singlet exciton energy and the triplet exciton
energy derived from the first dopant. Since the second and third
dopants have relatively narrow FWHM as compared with the first
dopant, the OLED 600 can enhance its luminous efficiency and color
purity.
Each of the EML1 662, the EML2 664 and the EML3 666 includes the
first host, the second host and the third host, respectively. For
example, each of the first to third hosts may be the same or
different from each other. As an example, each of the first to
third hosts may include the organic compound having the structure
of any one in Chemical Formulae 1 to 6. In one exemplary
embodiment, the first dopant may include, but are not limited to,
the organic compound having the structure of any one in Chemical
Formula 7. In an alternative embodiment, the first dopant may
include, but are not limited to, DMAC-TRZ, DMAC-DPS, ACRSA, Cz-VPN,
TcZTrz, DczTrz, DDczTrz, CC2BP, BDPCC-TPTA, BCC-TPTA, DMOC-DPS,
DPCC-TPTA, Phen-TRZ, Cab-Ph-TRZ, 4CzIPN, 4CZFCN,
10-(4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-10H-spiro[acridine-9,9'-xa-
nthene] and/or SpiroAC-TRZ.
Each of the second and third dopants may have narrow FWHM and have
luminous spectrum having large overlapping area with the absorption
spectrum of the first dopant. As an example, each of the second and
third dopants may independently include, but are not limited to, an
organic compound having a quinolino-acridine core such as
5,12-dimethylquinolino[2,3-b]acridine-7,14(5H, 12H)-dione,
12-diethylquinolino[2,3-b]acridine-7,14(5H, 12H)-dione,
5,12-dibutyl-3,10-difluoroquinolino[2,3-b]acridine-7,14(5H,
12H)-dione,
5,12-dibutyl-3,10-bis(trifluoromethyl)quinolino[2,3-b]acridine-7,14(5H,
12H)-dione,
5,12-dibutyl-2,3,9,10-tetrafluoroquinolino[2,3-b]acridine-7,14(5H,
12H)-dione, DCJTB and any metal complexes which can emit light of
red, green or blue color.
In this case, the energy levels among the first to third hosts and
the first to third dopant are the same as described in FIG. 10.
In one exemplary embodiment, each of the second and third hosts in
the EML2 664 and the EML3 666 may have weigh ratio equal to or more
than the weight ratio of the second and third dopants within the
same EMLs. The weight ratio of the first dopant in the EML1 662 may
be more than the weight ratio of the second and third dopants in
the EML2 664 and the EML3 666. In this case, it is possible to
transfer enough exciton energy from the first dopant in the EML1
662 to the second and third dopants in the EML2 664 and the EML3
666 through FRET energy transfer mechanism.
When the EML2 664 is disposed adjacently to the first EBL 655 in
one exemplary embodiment, the second host, which is included in the
EML2 664 together with the second dopant, may be the same material
as the first EBL 655. In this case, the EML2 664 may have an
electron blocking function as well as an emission function. In
other words, the EML2 664 can act as a buffer layer for blocking
electrons. In one embodiment, the first EBL 655 may be omitted
where the EML2 664 may be an electron blocking layer as well as an
emitting material layer.
When the EML3 666 is disposed adjacently to the first HBL 675 in
another exemplary embodiment, the third host, which is included in
the EML3 666 together with the third dopant, may be the same
material as the first HBL 675. In this case, the EML3 666 may have
a hole blocking function as well as an emission function. In other
words, the EML3 666 can act as a buffer layer for blocking holes.
In one embodiment, the first HBL 675 may be omitted where the EML3
666 may be a hole blocking layer as well as an emitting material
layer.
In still another exemplary embodiment, the second host in the EML2
664 may be the same material as the first EBL 655 and the third
host in the EML3 666 may be the same material as the first HBL 675.
In this embodiment, the EML2 664 may have an electron blocking
function as well as an emission function, and the EML3 666 may have
a hole blocking function as well as an emission function. In other
words, each of the EML2 664 and the EML3 666 can act as a buffer
layer for blocking electrons or hole, respectively. In one
embodiment, the first EBL 655 and the first HBL 675 may be omitted
where the EML2 664 may be an electron blocking layer as well as an
emitting layer and the EML3 666 may be a hole blocking layer as
well as an emitting material layer.
In an alternative embodiment, the lower EML 660 may have a
single-layered structure as illustrated in FIGS. 2 and 5. In this
case, the lower EML 660 may include a host and a first dopant which
may be a delayed fluorescent material, or a host, a first dopant
which may be a delayed fluorescent material and a second dopant
which may be a fluorescent or phosphorescent material.
In another alternative embodiment, the lower EML 660 may have a
double-layered structure as illustrated in FIG. 7. In this case,
the lower EML 660 may include a first EML and a second EML. The
first EML may include a first host and a first dopant which may be
a delayed fluorescent material, and the second EML may include a
second host and a second dopant which may be a fluorescent or
phosphorescent material.
In another exemplary embodiment, an OLED of the present disclosure
may further includes a third emitting unit disposed between the
second emitting unit 730 and the second electrode 620 and a second
CGL disposed between the second emitting unit 730 and the third
emitting unit. In this case, at least one of the first emitting
unit 630, the second emitting unit 730 and the third emitting unit
may include the organic compound having the structure of any one in
Chemical Formulae 1 to 6 as the host.
Synthesis Example 1: Synthesis of Compound 1
(1) Synthesis of Intermediate 1-1 (Methyl-2-(pyridin-3-yl-amino)
benzoate)
##STR00042##
5.30 g (35 mmol) of methyl-2-aminobenzoate, 5.0 g (32 mmol) of
3-bromopyridine, 14.3 g (44 mmol) of Cs.sub.2CO.sub.3 and 50 mL of
toluene was placed into 250 mL three neck distillation round bottom
flask and then nitrogen was substituted. 0.072 g (0.32 mmol) of
palladium (II) acetate (Pd(OAc).sub.2) and 0.56 g (0.96 mmol) of
4,5-bis(diphenylphosphine)-9,9-dimehtylxanthene (Xantphos) were
added into the nitrogen substituted flask and then the solution was
stirred for 12 hours at 110.degree. C. The proceeding status of the
reaction was confirmed using TLC (thin layer chromatography) and
then the flask was cooled down to room temperature. After salts
produced in the course of the reaction and excessive
Cs.sub.2CO.sub.3 were removed by Celite filter, the filtrate was
distilled under reduced pressure and then was purified by solid
column chromatography. The solvent was removed to give 4.5 g
(yield: 66%) of yellow solid intermediate 1-1.
(2) Synthesis of Intermediate 1-2
(Diphenyl-(2-pyridin-3-yl-amino)-phenyl) methanol)
##STR00043##
2.0 g (8.7 mmol) of intermediate 1-1 and 25 mL of THF were placed
into 100 mL three neck distillation round bottom flask and then
nitrogen was substituted. Phenylmagnesium bromide (26 mmol) was
added drop wisely to the flask at 0.degree. C. with stirring. After
dropping was completed, the solution was stirred for 12 hours at
room temperature. The proceeding status of the reaction was
confirmed using TLC. After reactants were distilled under reduced
pressure and then was purified by solid column chromatography. The
solvent was removed to give 2.8 g (yield: 91%) of yellow solid
intermediate 1-2.
(3) Synthesis of Intermediate 1-3
(5,5-Diphenyl-5,10-dihydrobenzo[1,7]naphthyridine)
##STR00044##
2.8 g (7.9 mmol) of intermediate 1-2, 40 mL of acetic acid and 4 mL
of HCl were placed into 250 mL three neck distillation round bottom
flask, and then the solution was stirred for 12 hours at 70.degree.
C. The solid produced in the course of the reaction was obtained by
reduced filter and then was purified by solid column
chromatography. The solvent was removed and a crude product was
recrystallized using methylene chloride (MC) and hexane to give 2.3
g (yield: 86%) of yellow solid intermediate 1-3.
(4) Synthesis of Intermediate 1-4
(9-(3-Bromophenyl)-9H-carbazole)
##STR00045##
145 mL (53 mmol) of 1-bromo-3-iodo benzene, 8.7 g (52 mmol) of
carbazole, 10.1 g (159 mmol) of Cu powder, 22 g (159 mmol) of
K.sub.2CO.sub.3 and 150 mL of DMF were placed into 250 mL three
neck distillation round bottom flask, and then the solution was
stirred for 24 hours at 130.degree. C. The proceeding status of the
reaction was confirmed using TLC and then the flask was cooled down
to room temperature. After salts produced in the course of the
reaction and excessive K.sub.2CO.sub.3 were removed by Celite
filter, the solution was extracted with 20 mL of distilled water
and 150 mL (.times.3) of EtOAc. The organic solution was dried by
MgSO.sub.4 and then distilled under reduced pressure to obtain
solid mixture. The solid mixture was purified by silica column
chromatography to give 14.9 g (yield: 89%) of intermediate 1-4.
(5) Synthesis of Compound 1
(10-(3-(9H-carbazol-9-yl)phenyl)-5,5-diphenyl-5,10-dihydrobenzo[b][1,7]na-
phthyridine)
##STR00046##
1.61 g (5 mmol) of intermediate 1-4, 1.5 g (4.5 mmol) of
intermediate 1-3, 1.12 g (10 mmol) of potassium tert-butoxide
(t-BuOK) and 40 mL of toluene were placed into 100 mL three neck
distillation round bottom flask, and then nitrogen was substituted.
0.22 g (0.23 mmol) of tris(dibenzylideneacetone) dipalladium (0)
(Pd.sub.2(dba).sub.3) and 0.18 g (0.9 mmol) of
tri-tert-butylphosphine (P(tBu).sub.3) were placed into the
nitrogen substituted flask, and then the solution was stirred for
12 hours. The proceeding status of the reaction was confirmed using
TLC and then the flask was cooled down to room temperature. After
salts produced in the course of the reaction and excessive t-BuOK
were removed by Celite filter, the filtrate was distilled under
reduced pressure and then was purified by solid column
chromatography. The solvent was removed and a crude product was
recrystallized using methylene chloride and hexane to give 1.7 g
(yield: 66%) of white solid Compound 1.
Synthesis Example 2: Synthesis of Compound 2
(1) Synthesis of Intermediate 2-1
(9-(4-bromophenyl)-9H-carbazole)
##STR00047##
Synthetic process was performed in the same manner as in the
synthesis of the intermediate 1-4 except that 145 mL (53 mmol) of
1-bromo-4-iodobenzene and 8.7 g (52 mmol) of carbazole were used as
reactants to give 6.2 g (yield: 52%) of Intermediate 2-1.
(2) Synthesis of Compound 2
(10-(4-(9H-carbazol-9-yl)phenyl)-5,10-dihydro-5,5-diphenylbenzo[b][1,7]na-
phthyridine)
##STR00048##
Synthetic process was performed in the same manner as in the
synthesis of the Compound 1 except that 0.7 g (1.4 mmol) of
intermediate 2-1 and 0.52 g (1.5 mmol) of intermediate 1-3 were
used as reactants to give 0.6 g (yield: 75%) of white solid
Compound 2.
Synthesis Example 3: Synthesis of Compound 3
(1) Synthesis of Intermediate 3-1
(10-(3-bromophenyl)-9,9-diphenyl-9,10-dihydroacridine)
##STR00049##
12 g (43 mmol) of 1-bromo-3-iodobenzene, 12 g (36 mmol) of
diphenylacridine, 0.343 g (1.8 mmol) of CuI, 6.92 g (72.0 mmol) of
sodium tert-butoxide (NaOt-Bu), 0.822 g (7.20 mmol) of
tert-1,2-diaminocyclohexane and 150 mL of 1,4-dioxane were placed
into 250 mL three neck distillation round bottom flask, and then
the solution was stirred for 12 hours at 100.degree. C. The
reaction mixture was cooled down to room temperature, 100 mL of
methanol was added into the solution, and then the solution was
distilled under reduced pressure to recover a precipitate. The
precipitated reaction mixture was purified by silica column
chromatography to give 10.1 g (yield: 58%) of intermediate 3-1.
(2) Synthesis of Compound 3
(10-(3-(9,9-diphenylacridin-10(9H)-yl)phenyl)-5,5-diphenyl-5,10-dihydrobe-
nzo[b][1,7]naphthyridine)
##STR00050##
Synthetic process was performed in the same manner as in the
synthesis of the Compound 1 except that 0.7 g (1.4 mmol) of
intermediate 3-1 and 0.52 g (1.5 mmol) of intermediate 1-3 were
used as reactants to give 0.8 g (yield: 78%) of white solid
Compound 3.
Synthesis Example 4: Synthesis of Compound 4
(1) Synthesis of Intermediate 4-1
(10-(4-bromophenyl)-9,9-diphenyl-9,10-dihydroacridine)
##STR00051##
Synthetic process was performed in the same manner as in the
synthesis of the intermediate 3-1 except that 7.6 g (36 mmol) of
diphenylacridine and 36 g (127 mmol) of 1-bromo-4-iodobenzene were
used as reactants to give 11 g (yield: 80%) f intermediate 4-1.
(2) Synthesis of Compound 4
(5,10-dihydro-5,5-diphenyl-10-(4-(9,9-diphenylacridin-10(9H)-yl)phenyl)be-
nzo[b][1,7]naphthyridine)
##STR00052##
Synthetic process was performed in the same manner as in the
synthesis of the Compound 1 except that 0.7 g (1.4 mmol) of
intermediate 4-1 and 0.52 g (1.5 mmol) of intermediate 1-3 were
used as reactants to give 0.85 g (yield: 85%) of white solid
Compound 4.
Synthesis Example 5: Synthesis of Compound 5
(1) Synthesis of Intermediate 5-1
(3-(9H-carbazol-9-yl)-9H-carbazole)
##STR00053##
35.3 g (143.5 mmol) of 3-bromo-carbazole, 20 g (119.6 mmol) of
carbazole, 60 g (60 mmol) of CuI, 97.4 g (229 mmol) of
Cs.sub.2CO.sub.3 and 7.18 g (119.6 mmol) of ethylene diamine were
dissolved in 700 mL of toluene, the solution was refluxed for 12
hours and then the solution was cooled down to room temperature.
After the solution was extracted with 150 mL (.times.4) of EtOAc,
the moisture of the organic layer was dried by MgSO.sub.4. The
organic solvent was removed and then a crude product was purified
by silica tube chromatography to give 33 g (yield: 80%) of
intermediate 5-1.
(2) Synthesis of Intermediate 5-2
(9-(9-(3-bromophenyl)-9H-carbazol-6-yl)-9H-carbazole)
##STR00054##
Synthetic process was performed in the same manner as in the
synthesis of the intermediate 1-4 except that 10.0 g (30 mmol) of
intermediate 5-1 and 18 g (64 mmol) of 1-bromo-3-iodobenzene were
used as reactants to give 12.1 g (yield: 83%) of intermediate
5-2.
(3) Synthesis of Compound 5
(10-(3-(9H-carbazol-9-yl)phenyl)-5,5-diphenyl-5,10-dihydrobenzo[b][1,7]na-
phthyridine)
##STR00055##
Synthetic process was performed in the same manner as in the
synthesis of the Compound 1 except that 2.04 g (5 mmol) of
intermediate 5-2 and 1.5 g (4.5 mmol) of intermediate 1-3 were used
as reactants to give 2.0 g (yield: 60%) of white solid Compound
5.
Synthesis Example 6: Synthesis of Compound 6
(1) Synthesis of Intermediate 6-1
(9-(3-bromo-5-(9H-carbazol-9-yl)phenyl)-9H-carbazole)
##STR00056##
52 g (0.31 mmol) of carbazole and 13 g (0.31 mmol) of NaH (60%
suspension in oil) were dispersed in 250 mL of anhydrous DMF and
then the dispersion was stirred for 1 hour at room temperature. 12
mL (0.10 mol) of 3,5-difluorobromobenzene was added slowly into the
dispersion using dropping funnel, and the solution was stirred for
12 hours at 130.degree. C. The reaction solution was cooled down to
room temperature and then mixed solution of EtOH/H.sub.2O (10/1)
was added to form a precipitate. The precipitated product was
recrystallized by methylene chloride and methanol to give 39.3 g
(yield: 81%) of intermediate 6-1.
(2) Synthesis of Compound 6
(10-(3,5-di(9H-carbazol-9-yl)phenyl)-5,10-dihydro-5,5-diphenylbenzo[b][1,-
7]naphthyridine)
##STR00057##
Synthetic process was performed in the same manner as in the
synthesis of the Compound 1 except that 2.44 g (5 mmol) of
intermediate 6-1 and 1.5 g (4.5 mmol) of intermediate 1-3 were used
as reactants to give 2.17 g (yield: 65%) of white solid Compound
6.
Synthesis Example 7: Synthesis of Compound 7
(1) Synthesis of Intermediate 7-1
(9-(3-fluoro-5-bromo-phenyl)-9H-carbazole)
##STR00058##
Synthetic process was performed in the same manner as in the
synthesis of the Compound 1 except that 10 g (59.8 mmol) of
carbazole and 11.6 g (60 mmol) of 3,5-difluorobromobenzene were
used as reactants to give 9.8 g (yield: 48%) of intermediate
7-2.
(2) Synthesis of Intermediate 7-1
9-(3-(3-(9H-carbazol-9-yl)-9H-carbazol-9-yl)-5-bromophenyl)-9H-carbazole)
##STR00059##
Synthetic process was performed in the same manner as in the
synthesis of the Compound 1 except that 5 g (14.7 mmol) of
intermediate 7-1 and 4.89 g (14.7 mmol) of intermediate 5-1 were
used as reactants to give 5.1 g (yield: 53%) of intermediate
7-2.
(3) Synthesis of Compound 7
(10-(3-(3-(9H-carbazol-9-yl)-9H-carbazol-9-yl)-5-(9H-carbazol-9-yl)phenyl-
)-5,10-dihydro-5,5-diphenylbenzo[b][1,7]naphthyridine)
##STR00060##
Synthetic process was performed in the same manner as in the
synthesis of the Compound 1 except that 3.26 g (5 mmol) of
intermediate 7-2 and 1.5 g (4.5 mmol) of intermediate 1-3 were used
as reactants to give 2.08 g (yield: 51%) of white solid Compound
7.
Synthesis Example 8: Synthesis of Compound 8
(1) Synthesis of Intermediate 8-1
##STR00061##
Synthetic process was performed in the same manner as in the
synthesis of the intermediate 3-1 except that 30.4 g (84.0 mmol) of
1,3-dibromo-5-iodobenzene and 30.2 g (90.6 mmol) of
diphenylacridine were used as reactants to give 15.4 g (yield: 32%)
of Intermediate 8-1.
(2) Synthesis of Intermediate 8-2
##STR00062##
Synthetic process was performed in the same manner as in the
synthesis of the intermediate 1-4 except that 15.4 g (27.1 mmol) of
intermediate 8-1 and 4.5 g (26.9 mmol) of carbazole were used as
reactants to give 15.7 g (yield: 76%) of intermediate 8-2.
(3) Synthesis of Compound 8
(10-(3-(9H-carbazol-9-yl)-5-(9,9-diphenylacridin-10(9H)-yl)phenyl)-5,10-d-
ihydro-5,5-diphenylbenzo[b][1,7]naphthyridine)
##STR00063##
Synthetic process was performed in the same manner as in the
synthesis of the Compound 1 except that 3.27 g (5 mmol) of
intermediate 8-2 and 1.5 g (4.5 mmol) of intermediate 1-3 were used
as reactants to give 1.88 g (yield: 46%) of Compound 8.
Experimental Example 1: Measurement of Physical Properties of
Organic Compound
Physical properties for the Compounds 1 to 8 were evaluated.
Particularly, HOMO energy level, LUMO energy level, energy level
bandgap (LUMO-HOMO, Eg) and triplet energy level (T.sub.1) and for
each of the compounds were evaluated. For the comparison, physical
properties for the Reference compound (Ref.) having the following
structure was evaluated. The measurement results are indicated in
the following Table 1.
##STR00064##
TABLE-US-00001 TABLE 1 Luminescence Properties of Organic Compound
HOMO* LUMO* Eg T.sub.1* Compound (eV) (eV) (eV) (eV) Ref. -5.81
-2.22 3.59 3.01 Compound 1 -5.93 -2.16 3.77 3.27 Compound 2 -6.05
-2.11 3.96 2.83 Compound 3 -5.98 -2.22 3.76 3.29 Compound 4 -5.97
-2.27 3.70 2.78 Compound 5 -6.22 -2.20 4.02 3.17 Compound 6 -6.16
-2.34 3.82 3.11 Compound 7 -6.21 -2.16 4.05 3.12 Compound 8 -6.01
-2.02 3.99 3.21 *HOMO: Film (100 nm/ITO) by AC3; *LUMO: Calculated
from film absorption edge; *T.sub.1: Calculated by Gaussian
ED-DFT(time-dependent density functional theory), solution(toluene)
by FP-8600
As indicated by Table 1, each of Compounds 1-8 showed an adequate
HOMO energy level, LUMO energy level and energy level bandgap as
used luminous material in an emitting layer. Also, each of
Compounds 1-8 showed a high triplet energy level as a host.
Considering the triplet energy levels of the Compounds, it was
found that the use of those compounds in combination with a delayed
fluorescent material was suitable for exciton energy transfer so
that good luminous efficiency was implemented while reducing the
non-emission quenching.
Example 1: Fabrication of Organic Light Emitting Diode (OLED)
An organic light emitting diode was fabricated using Compound 1
synthesized in the Synthesis Example 1 as a host in an emitting
material layer (EML). An ITO (including reflective layer) attached
glass substrate with 40 mm.times.40 mm.times.0.5 mm was
ultrasonically cleaned with isopropyl alcohol, acetone and
distilled water for 5 minutes and then dried in an oven at
100.degree. C. The cleaned substrate was treated with O.sub.2
plasma in a vacuum for 2 minutes and transferred to a deposition
chamber in order to deposit other layers on the substrate. An
organic layer was deposited by evaporation by a heated boat under
10.sup.-7 torr in the following order. The deposition rate of the
organic layer was set to 1 .ANG./s.
A hole injection layer (HIL) (HAT-CN; 50 .ANG.); a hole transport
layer (HTL) (TAPC, 500 .ANG.); an electron blocking layer (EBL)
(DCDPA; 100 .ANG.); an emitting material layer (EML) (Compound 1
(host): TcTrz (delayed fluorescent material)=70:30 by weigh ratio;
250 .ANG.); a hole blocking layer (HBL) (TSPO1; 100 .ANG.); an
electron transport layer (ETL) (TPBi; 300 .ANG.); an electron
injection layer (EIL) (LiF; 15 .ANG.); and a cathode (Al; 1000
.ANG.).
And then, capping layer (CPL) was deposited over the cathode and
the device was encapsulated by glass. After deposition of emissive
layer and the cathode, the OLED was transferred from the deposition
chamber to a dry box for film formation, followed by encapsulation
using UV-curable epoxy and moisture getter. The manufacture organic
light emitting diode had an emission area of 9 mm.sup.2.
Examples 2 to 6: Fabrication of OLED
An organic light emitting diode was manufactured as the same
process and the same materials as Example 1, except using Compound
3 (Example 2), Compound 5 (Example 3), Compound 6 (Example 4),
Compound 7 (Example 5) and Compound 8 (Example 6) as the host in
place of Compound 1 in the EML.
Comparative Example: Manufacture of OLED
An organic light emitting diode was manufactured as the same
process and the same materials as Example 1, except using Reference
Compound (Ref.) as the host in place of Compound 1 in the EML.
Experimental Example 2: Measurement of Luminous Properties of
OLED
Each of the organic light emitting diode fabricated in Examples 1
to 6 and Comparative Example was connected to an external power
source, and luminous properties for all the diodes were evaluated
using a constant current source (KEITHLEY) and a photometer PR650
at room temperature. In particular, driving voltage (V), current
efficiency (cd/A), external quantum efficiency (EQD; %) and color
coordinates (CIEx and CIEy) at a current density of 10 mA/cm.sup.2
of the light emitting diodes of Examples 1 to 6 and Comparative
Example were measured. The results thereof are shown in the
following Table 2.
TABLE-US-00002 TABLE 2 Luminous Properties of OLED Sample V cd/A
EQE (%) CIEx, CIEy Ref. 3.9 32.1 18.3 0.161, 0.257 Example 1 3.5
40.4 25.2 0.160, 0.255 Example 2 3.4 40.9 25.6 0.159, 0.252 Example
3 3.6 39.1 23.7 0.163, 0.250 Example 4 3.8 35.3 21.2 0.160, 0.250
Example 5 3.7 37.8 22.7 0.159, 0.249 Example 6 3.6 39.9 24.1 0.162,
0.252
As indicated in Table 2, compared with the OLED including reference
compound as the host in the EML of the Comparative Example, the
OLED including the organic compounds as the host in the EML of the
Examples reduced its driving voltage up to 12.8%, and improved its
current efficiency up to 27.4% and its external quantum efficiency
up to 39.9% It was confirmed that the OLED can lower its driving
voltage and improve its luminous efficiency by applying the organic
compound of the present disclosure into an emitting unit.
Accordingly, an organic light emitting device such as an organic
light emitting display device having reduced power consumption and
improved luminous efficiency and luminous lifetime can be realized
by using the organic light emitting diode into which the organic
compound of the present disclosure is applied.
While the present disclosure has been described with reference to
exemplary embodiments and examples, these embodiments and examples
are not intended to limit the scope of the present disclosure.
Rather, it will be apparent to those skilled in the art that
various modifications and variations can be made in the present
disclosure without departing from the spirit or scope of the
invention. Thus, it is intended that the present disclosure cover
the modifications and variations of the present disclosure provided
they come within the scope of the appended claims and their
equivalents.
These and other changes can be made to the embodiments in light of
the above-detailed description. In general, in the following
claims, the terms used should not be construed to limit the claims
to the specific embodiments disclosed in the specification and the
claims, but should be construed to include all possible embodiments
along with the full scope of equivalents to which such claims are
entitled. Accordingly, the claims are not limited by the
disclosure.
* * * * *